If you don't mind, I'm just going to ramble on about competition shooting for a bit, and hopefully, there will be a few semi-good ideas that will help you out:
First, congrats on taking the initiative to get out and shoot a match. I feel like (no insult intended) that unless you just got out of the SEALs or were on the SWAT team for the past 20 years, most people aren't going to go out and shoot a perfect score on their first couple matches. I may very well be wrong, and I'm not the best shooter out there by any means, so again, I'm not trying offend anyone, and I'm not suggesting that this is what you're thinking, but I think its a little unrealistic to take someone who may be a fantastic shooter, and then throw them into a competition that involves more than just shot placement, and expecting them to be better than Doc Holiday. The only reason why I'm saying this is that you mentioned getting discouraged shooting in "open class" and I'm thinking that you might be more successful in the long-term if you're main goal on day one was to be safe, and have fun. Just something to think about.
Which gun do you enjoy shooting more? If you're heart skips a beat when you pick up that Glock, then go for open, give it your best shot, and have a blast. If the 1911 makes your heart sing, then single stack or limited 10 might be a great place to start.
What are you trying to get out of the match? I know you specified USPSA, but its not the only game out there. IDPA is a lot of fun, and I feel like its great place to be a 1911 shooter. Some clubs also have their own smaller matches, and your pistols might suit you well in a falling plate or steel challenge type match. Where are you from? There might be someone on the board with some insight into the local matches in your area.
Another thing to consider is what you gear you have or can borrow. Holsters suitable for competition? mag pouches? magazines? My first USPSA match, about half my mags were ones I borrowed from a shooting buddy.
If it was me, I'd just shoot whichever one you think would be more fun, and say to heck with scores. You'll get better. Its one of the things I love about shooting competitively: You get a chance to watch someone who is light-years ahead of you shoot, then ask them questions, and they can see you shoot, and share the tips of the trade.
Let us know how it goes, and don't forget, there are a lot of games out there, and you might like some more than others, so try all of them.
I really hope this helps, and if ya'll will tolerate it, I'd like to remind everyone of the words of one Inspector Sledge Hammer: "A gun is a dangerous weapon, and if used properly, a WONDERFUL source of entertainment."
Seriously though, shoot safe, have fun, and I really do hope that something I wrote here was in some way useful to you.
-Chris "The Kayak-Man" Johnson