I just live in flip flops. I couldn't contemplate wearing anything else. I always carry some talc just in case of rubbing, but hardly ever need it. Some people say to use vaseline, but I find a quick dust of talc does the job if I have become particularly sweaty or damp for any reason. There's been a lot of talk about Crock shoes, but they just look so sweaty to me. I can't imagine having my feet enclosed in anything!
Feet do tend to get grubby, particularly around the heels when wearing flip flops, but I find a quick rub with a soapy flannel each day does the trick.