My front brake is not biting hard enough (takes a long time to stop).  First thing I checked was the pads, and grooves are still clearly visible so not all the material has been eaten away.  Next I thought it was old fluids (haven't been changed for 4 years).  Changed brake fluid making sure no bubbles are coming during the bleeding process.  Front brake is still very weak, and application of the lever is kinda soft.  I don't know if I should call it spongy since I am not sure what it means.  If brakes are spongy, does it mean that the lever does not snap back immediately when you release it?  If that's the definition than mine is not, it snaps back. 

What else would you recommend me to look at?

Thanks as always

I'm not entirely sure that a bike master cylinder is the same as a car's, but if you were talking about a car, I'd recommend replacing the master...

Might be time to replace the stock rubber line, not sure how old it is. Braided S/S lines make a big difference. I replace them on every bike, even if brand new.

Also, the pads may be glazed. Scuff them a little.

+1 on the old line. Happened to me before. Maybe the seals in the caliper are busted and there's a fluid leak?

definitely no leaks - fluid level is very stable and no traces of braking fluid anywhere throughout the years.  The stock line is about 4 years old too.  Do you think it's time to replace it? Visually it looks to be in a very good shape (no cracks, still pretty elastic, etc.)  How could it affect the braking?  And if you still recommend to change it, could you point to the braded line you mentioned, if it's available online?

4 years old should not be bad, unless stored in direct sunlight most of the time.

Stock rubber lines will expand while under use. This gives you the impression of spongy brakes.

Sorry I cannot help with a GS braided line. I do not use GS forks and brakes. There have been plenty of posts regarding them though.

Stored in garage, by the looks of it lines in pretty good shape... if there are no bubbles when the fluid comes out the bleeder valves does this pretty much exclude air in the system?  i guess next step is taking the pads apart, everything else that could be logically ruled out without doing that seems to have been checked, I am guessing...right?

It is possible to still have an air bubble in the master cylinder, being the highest point in the brake system. I like to add a bleeder valve at the m/c to help remove all of the air.

opened master cylinder, pumped the break - no bubbles coming up from the bottom of the mc either.  Does that rule out air issues, or can air still be in the system?
Read about glazed pads - don't think that's my case, just judging by how i used them 

Sounds like the Fluid is "Blowing" Past the Cup on the end of the Plunger.I would just rebuild the Master.When you Pull the lever How far can you pull it back?You should still have a Lot of Travel Left that Isn't used at full brake.also when you pull the lever see if the Brake Line is Expanding.it should expand just a Little but if there are Places where it is Ballooning out ditch it and get a Braided Line.

I'd try bleeding the brake again with a helper, preferably someone with some evperience. When I put a new line on my bike, It took a really long time to get all the air out, so make sure you're doing it for long enough.

Make sure that no grease oil or other slick stuff got on your pads. Clean them up with brake cleaner really well, maybe even let the pads soak in solvent for a while. Then scuff the pads and try again.

With a 4 yr old line, you should be okay, but if you end up replacing it, it's probally cheaper to go to an aftermarket or home made braided line than it is to order a new rubber one from suzuki, and it'll work better.

Start with the simplest and cheapest possibilities and then work your way up to the more expensive ones