Never been a huge fan of Birkenstocks, but I did have one pair I liked to wear as an easy slip on/slip off kind of shoe. Always wore them with socks. Don't care if that's gausche. My feet get cold, and I actually prefer the look better. Always with jeans.
However, when the soles started literally disentegrating I went in search of another pair. They had changed them to add a little ridge under the toes and the footbed was hard. I guess it's meant to help the toes grab the shoe, but it hurts my feet, so no more. Luckily, I was able to find some knock-offs that work just fine that don't have the hard footbed and toe ridges at, of all places, Shoe Carnival. Actually ended up with 2 pair by 2 different companies. I believe one of them were Steve Madden's Madden Girl and the other were White Mountain. Saved myself a bit of money too since I could get 2 pair for probably less than one pair of Birkenstocks. Don't kow the style, it's just the slip-on with two straps, one across the toes and one across the instep.