The wife and I use GoreTex rain suits, the same type we issue to our motor officers. They work great, and have liners for the pants and jacket for cold weather protection even when it is not raining. I used mine this morning with my Gerbing heated liners and they worked great. Expensive, but worth it for the comfort.
Frog Toggs are worth there weight. Maybe I souldn't have put it that way since they are Soooo light in weight. They are the best for the amount they cost. You can get better BUT it will cost you 4 or 5 times more money.
While I have a couple of sets of Frogg Toggs and they are very good, my main problem with them is they are rather delicate and will wear out with regular (heavy) use in 12 to 18 months. Therefore, I'd suggest you invest in something like a FirstGear Jacket and pants that are lightweight, but also waterproof. They will actually do every bit as well as the Frogg Toggs, but won't wear out and pack easily and are compact so you can keep them on board 365 days a year.
Overall much better, durable and nice looking too,
Best thing about Frogg's is that they pack so well. I put mine in zip lock bags and they take up very little space. I've not had that much need for them, but they work very well when called on. I don't care to ride in the rain, so I'll pull off and wait it out, unless I have no choice.
Got the 1st Gear 2 piece rain suits they work very well, roll up and pack in their included bag and don't take significant space in the saddle bags. They're also great for the chilly night. Cost about $100/set, probably HDL has them cheaper but I got them at my local Honda dealer.
Motoport/Cycleport goretex type rainsuits are worth the money. Breathable, 100% waterproof, windproof, and pack small. We started with PVC suits years ago, went to vented PVC, tried Frog Toggs, then went for the real deal. If you do long trips, expecially in the heat they are worth the investment, I just wish that I had bought them first instead of last, I would have saved a ton of money.
I've been through a few evolutions of rain suits. I started off with a Wal-Mart PVC suit. It was comlpetely waterproof, but couldn't hold up to MC use and the high winds - shredded! I then got a nice Nelson Rigg PVC coated polyester two piece suit (the AX-1). Great - completely waterproof (even for long exposures) and very durable. But, heavy and hot. I have experiemented with the PVC/Nylon suits (by Nelson Rigg 'Stormrider'- or Tourmaster 'Elite'). Good as well - waterproof (but seem to eventually soak through after prolonged rains/high speed driving), durable, and much lighter/more comfortable than the heavier PVC polyester. I have a few friends with the Frogg Toggs. The only negatives I've heard is they are somewhat fragile (can tear slipping boots through, etc.), they don't do much for standing water (sitting in a wet set results in wet pants!), and it seems some get "bad batches" that leak (but reportedly immediately replaced by the company). I have yet to get a set of the Toggs, but considering it. They do pack small (the Elite suits pack smaller than the AX-1's, but not as small as the Toggs).
In general, I think 2 peice suits are more comfortable, easier to put on/take off, and more versatile (if you end up with a waterproof winter jacket, you could then just pack the pants, etc.).
Any quality suit will have sealed seams, a storm flap (to keep rain from soaking through the zipper), some sort of ventalation, and suspenders are good too. If you have big feet, pay attention to how far the legs unzip for entry (the AX-1's are a little on the small side for my 13's) - saves a lot of hopping around on one foot trying to get your feet in!
Overall, I lean toward the Tourmaster Elite 2 peice.
I have a Honda racing jacket, it is always waterproof plus it is very warm with the linner, the linner can be removed easilly and vents opened in hot weather,great all around jacket for me in temps from 15-90 degrees. I have tried several options for waterproof pants but have not been well satisfied with any so far but am still looking. As many others have suggested avoid the the PVC and other non breathable types they are miserable and in the long run mostly a waste of money.
If you have the money, the Aerostich Roadcrafter or Darien suits are worth their weight in gold. They not only give you the weather protection you want but also give you excellent crash protection. We don't like to think about crash protection, but it happens, and short of race leathers, I can't think of anything I'd rather have my skin in than an Aerostich.
Given the choice - and I am - I'll pick crash protection that also gives me hours of wet weather ridability over raingear that doesn't offer any crash protection every time.
I have to vote for the Frogg Toggs. I have had the same pair for four years. I think I have used them at least 25-30 times and they still look and work like new. Dry in the humid weather and warm as well.
I do have a burn mark from wearing them on a Vulcan and getting too close to the exhaust. They did not burn through though. I was surprised about that.