The "rules" say that you shouldn't wear slip-on shoes with a suit, but I see that "rule" broken quite often. If you're wearing a suit in a conservative, professional environment, then you should just wear the lace-ups to avoid looking odd. If you're wearing the suit in a more loose, stylish environment, then wear whatever you want. Either way, I doubt that you'll be judged too harshly by how you keep your shoes on your feet. I like not having to lace my shoes too; most of my casual shoes have no laces, but when I wear a suit, I use laces. If you buy a pair that fits well, you won't have any discomfort.