Our son just got over his not wanting to wear the exact same pair of shoes at 24 months. He was growing out of them and I knew we'd have to do something soon. I ended up collecting all the toddler/baby shoes we had in our house, so sandals from last summer, DDs little girly shoes, Robeez and putting them in in a bin. I had his new sneakers and new sandals in there too. He loves playing in the bin and eventually started trying new shoes on. Now we can get him out of the house in just about any shoe/sandal we want him to be wearing.
He loves garbage, the truck, the bins, etc.. So when we needed him to wear a new winter hat, we told him he had to wear his 'garbage' hat and help daddy take the garbage out. Then afterwards we'd get all excited and say, Let's put on your garbage hat! He totally fell for it. (we've also done 'train' pants to get him to wear these cute pants he wouldn't put on...) Maybe try something like that with sandals?
Oh, we've also told DS he had to wear sandals because it was hot outside and shoes weren't for hot weather. Somehow that worked too. DS can be very particular at times, like he would only wear certain cloth diapers and certain covers and I want these green jammies not those green jammies...ah fun times.