The blue ones I bought are pretty substantial. They have a cloth lining and the rubber/latex is fairly thick and flexible. I generally don't ride in the rain unless I get caught in it, so they don't get a lot of use. I can't tell you how well they'd hold up under constant exposure to the elements...and I don't want to find out.
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In the PNW I ride on day trip for 6 to 10 hours in the rain. All my gear is breathable waterproof, so like Gore-Tex or similar (Gore-Tex lost the patent). Those black rubber gloves at Graingers are made for chemical resistance and specifically your probably looking at the ones for concrete. They work obviously, but are stiff rubber and have little dexterity. Then there are the surgical type which you will need to underneath other gloves. The gloves made for dishes are the best for dexterity and abrasion/laceration resistance. But at someone mentioned earlier they develop a funk. I worked for a concrete contractor for 12 years and we would spray those out with anti-funk after every use. One person mentioned that riding in the rain would do the same, but the real culprit is lack of oxygen and increased carbon dioxide inside the glove...no breathability and no air. Plus, with out breathability, after an hour or so you will be just as wet on the inside as the outside. Go with breathable waterproof you will be happy you did, just look at other sports like cycling or any high level activity type sport.

 

I just got these Sealskinz:

 

Those sealskin look like a great choice.

 

Another option would be kayak/paddling gloves from a sporting goods store like MEC. Not sure is have a style with gauntlets.

 

Well, it seems like the responses are all over the board. I decided to take a chance on a company that I've had good luck with. I've had a Tour Master Transitions 2 jacket and Overpant for years, and am still very satisfied with them. I also have a pair of Tour Master Polar-Tex gauntlet gloves for cold weather, and they've always kept my hands dry. I didn't mention in my original post that I need 3X gloves, which eliminates a bunch of brands immediately. Since Tour Master is accommodating for large/tall sizes and I have a good track record with them, I opted to order a pair of gloves in 3X. When Spring arrives it'll be interesting to see how these perform. I'll try to remember to post and update.

 

Fox Creek has some very nice ones that I have been wanting to get. Just had an email from them today 10% off. I can't remember what the code was but if you call them I'm sure they would tell you.

 

Code, I believe, is WINTER10 for the 10% discount.

 

Why wait. Just do a leak test and put 'em under running water.

 

Pretty sure you are correct and I thought that was it but didn't want to post if not certain. Your memory is better than mine!!