My feet are very sensitive on the bottom, so when outside walking, I need some kind of footwear. If I don't have footwear, I am at risk of injuring myself. That's how sensitive the bottoms of my feet are. However, if I am just sitting outside, I take off the footwear. It is just the walking outside that is the issue.
As far as what footwear I use, I have some easy slip on/off sneakers. They work best for me as sandals, flip flops or even slippers doesn't work for me.
Inside I am always barefoot.
I prefer barefoot. If you're going to be naked, then be fully naked. Now, while hiking or biking or where the ground hurts my feet, then appropriate footwear is required. I have been nude hiking and had on Hiking boots. I wore running shoes while running naked. Let's be smart about it.
For hiking I have a pair of quite minimalistic trail running shoes from the Merrell trail glove series which I use as backup when barefoot isn't possible. But usually they keep staying in the backpack. They are very lightweight and comfortable, but have a good grippy Vibram sole. I think the minimalistic design fits somehow with being naked, at least more then heavy hiking boots.
I prefer to be barefoot as much as possible. But when footwear is more comfortable or required, I like to wear rope sandals. While at a clothing optional campground in Arizona 3 yrs ago they were being sold by Trish of "Naked Hippies Way". I wear them all the time. With clothes too. Get lots of positive comments.
Sadly I have permanent damage to my metatarsals and can't go very long/far barefoot (which when nude completes the experience).
So I use Sketchers flip flops ('thongs' here in Australia) most of the time.
For nude hiking I use Merrill low tops which are sensational. When I get to destination though I slip them off to have some true nude time!
For hiking situations where barefoot is not possible or just too dangerous, I own a pair of very lightweight Merrell trail glove shoes, from an older version line. They have a good Vibram sole, but are quite minimalistic though. Usually they can stay in the backpack ;-)
We both have Tevas for walking around/hiking and sliders when by the pool. I also have a 25 cent pair of Walmart flip flops for use at our outdoor shower. If they get wet I just leave them out in the sun until they dry off. Uncomfortable as hell to walk in, though!
For hiking, I am a heavy boot kinda guy so I wear my custom-made Limmers when on the trail. So, in the mountains, it's boots, socks, and a pack.
For lesser walks, it's a pair of Tevas that have good grip and are very comfortable. With sensitive soles, as others have mentioned, barefoot is only for indoors.