These guys got it covered pretty well. Cherry Creek and Boyd are most popular up north.
But you also have Prospect lake in Springs. You have to get a pass to ride there and its only on certain days/times. There are a few standup guys there occasionally.
As for Pueblo... well if you are just getting into standups then it will ruin your experience quickly IMO. Pueblo is a JOKE for standups with the boat ramp and ANS inspection... huge no-wake zones everywhere and no way to hang out at the beach near your truck and gear unless you have someone to drive it around...
I live 5 minutes from Lake Pueblo and NEVER go there! It's sad because it used to be the best place to go when it was legal to shore-launch. So, as mentioned, several of us go to Lake Meredith or Lake Henry (about an hour east of Pueblo). Shore launch, camp, no regulations, etc. Standup paradise...
To answer your last question, I currently have a Toby T1, superfreak circus, Polaris Octane, SXR, 1200 Blaster and a couple SJ's!!!