I use Chamois Buttr, as do at least a few other cyclists I know. I don't bother with it on short rides, but anything 20 miles or more. I just squirt it directly into the shorts. Not shy about the quantity, either. It's a good idea to get out of your shorts as soon as you can after your ride to prevent any issues with bacteria or anything, whether you use a cream or not. I don't know if you can get a yeast infection or not, but I did read an article about getting out of your shorts asap for hygiene purposes. And, of course, wash them after each use.

I think you just to have figure out what works for you.