Although, its not technically lock picking I've also gotten pretty good using bypas tools to get into cars.
I hope they are your cars, or else you have expressed permission from the owners, cause that doesn't sound good.
I've gotten to where common 5 tumbler locks are little fun anymore.
Try 6 and 7 pin cylinders. I've got a son-of-a-bitch 7 pin restricted broach cylinder you can have a go at. Pick it and I will bow to your skill....
I was thinking for the next step of either taking up tubular lockpicking...
Definitely, the more knowledge and skills the better.