For Christmas, my wife bought me a cheap top case from Amazon like this one to replace my previous "Motocentric" tail bag, itself a copy of a Cortech bag.

I started with the tail bag strapped on the pillion area of the seat as most use it. It worked ok like this but there was no really good way to hook it on. Also when strapped on like this you basically can't use the stock helmet latches since they require you to lift the seat. And it screwed up my paint on the side/rear panels. So eventually I built a rack and put the tail bag on the rack which was far more useful.

The tail bag worked fine for what I needed it for. It had a ton of pockets so I could keep things like my insurance card and sunglasses with me at all times. It was big enough that I could cram my jacket in it and it readily held my laptop, by far the most frequent cargo. With the sides zipped to expand it would hold a 12-pack of Coke Zero which was important. I managed to cram all kinds of one-day grocery-trip stuff in there including family-size boxes of cereal and even an 8 lb bag of cat food one time. The big downside was that the zip opening really limited the size of items you could put in it, even making it tricky to get my 13" laptop in there. And of course after a year's use it faded to a bluish gray color even though I kept the bike garaged most of the time; this I assume was from simply sitting out while parked at my office on the rare occasions I rode to work.

The top box comes with a plastic base that it sort of snaps on and off of. I attached this to my rack with a combination of bolts and conduit clips. It's necessary to have some kind of rack to mount a case like this. It's far bigger, mostly deeper, than the tail bag it replaced and has the advent of a lock. While the hardware and the entire case is plastic easily defeated if you really want into it, it is at least enough when locked to prevent a would-be thief from simply opening it and running off with whatever's in there. Unlike the tail bag it won't expand large enough to carry a 12 pack of Coke Zero, but since it is rigid I can bungee-cord stuff on the pillion and it'll stay put. I don't like that you have to have the key to unlatch it at all. I do like that you can easily remove the entire case from the baseplate/rack so if I really wanted to carry it with me I could. I wish it had a mesh pocket of some kind inside it to hold my insurance card; as it is everything just bounces around. I will likely modify it with something like a sun-visor organizer/pocket from an auto parts store stuck inside somewhere with adhesive velcro. Another real upside is you can open it much wider than the tail bag so it easily fits whatever you put in it. I can fit a lot more groceries in it than I could the tail bag. The advertising suggests a 3/4 helmet will fit, but I haven't tried that.

A tail bag like the one I had will run about $60 for the knock off or like $75+ for the Cortech. The top box is a way better solution IMHO and is half the price. The big downside to the top box is you MUST have a rack, but this was easy enough for me to make one. But still, even if you buy one of the very expensive racks to put on your GS, this is a terrific option if you need to add a minimal amount of utility to your GS500.

Highly recommended! For the price, you can't go wrong. I don't love the way my GS500 looks with the case on there but the truth is I ride it a lot more since I can use it for errands and this makes commuting a snap. It's just too hot here to wear a backpack all the time, especially on top of a riding jacket. I would almost rather have panniers or side cases but that would require much more extensive modifications and fabrication to the GS and cost a lot more.

Top boxes are great for the practical machine. My bike came with a rack so it was a doddle to stick a giant 50L top-box on there. I keep my toolkit and locks in there, plus it can take my helmet and gloves, or a week's worth of shopping.

Welcome to the realm of useful motorcycles! Nothing beats hard cases on a motorcycle. My bike has locking side cases and a 50L top case that can hold 2 full face helmets with an additional rack on top of the top case. I don't know how anyone can use their bike around town or on trips without locking hard luggage. Where do you put your helmet(s) and gear when you get to where you are going?

For example, if my wife and I want to go for a hike, when we get there we put our helmets and gloves in the top case and our gear in the side cases. Do most people just wear all their gear wherever they are going?
If we want to pick up groceries on the way home we can pick up 4+ bags of groceries.
I've even hauled 4 cubic yards of bagged bark mulch from home depot.

The utility of a motorcycle is so much less without a full luggage set. Soft luggage is not secure and annoying to attach/remove from the bike and is generally not waterproof. I would only use soft luggage for offroad/adventure riding.

Pretty hard to beat locking hard cases, especially clip on locking ones. They make the bike less wieldy when loaded as well.
The easiest to handle Givis are the treckkers but they won't fit helmets. The best that fit helemts are the v35 . They have been around for a long time and you could probably pick up, with the GS500 racks, second hand easily. Very easy to install.

https://www.revzilla.com/motorcycle/givi-monokey-v35-side-cases

I am not a fan of most top boxes. Once loaded they put the weight exactly in THE worst place you can on a motorcycle to adversly effect the handling ( short of putting them on the forks). High and far back, moves you CoG up and back and away from the pendulum axis . If you have a single seat , moving them to just behind the rider will help mitigate the problem,  but the mounts usually won't let you get it there.

Quote from: gregjet on March 26, 2018, 01:17:37 PM
Pretty hard to beat locking hard cases, especially clip on locking ones. They make the bike less wieldy when loaded as well....

I am not a fan of most top boxes. Once loaded they put the weight exactly in THE worst place you can on a motorcycle to adversly effect the handling

My DIY rack won't support enough weight for this to be an issue, but I do agree side cases would be great if I really needed to carry more than +/- 10 lb of stuff. Probably will put that on my to-do list.

As bluesmudge pointed out, a big part of the case's utility is leaving things I would otherwise be wearing on my person with the bike when it's parked. In that case it doesn't really affect handling or riding dynamics