Just sneakers and dress shoes for me.
I’ve never been able to find sandals that felt comfortable, and I stopped wearing flip-flops after a nasty incident that happened when I was on vacation as a 10 year old - I fell down a flight of concrete steps and messed up my back; had I been wearing more snugly fitting shoes than flip-flops I probably wouldn’t have fallen.
I’d just bring a pair of good flip-flops or slides. Cheap dollar store ones won’t work for these purposes- I have a pair of good-quality Teva flip flops that have a comfortable molded soles and slightly-fancy looking thin crisscrossed straps that look nice enough to look reasonable with a dinner dress.
This was the only pair of shoes I took with me on a 3 month trip through Zambia, ZImbabwe and South Africa last summer. If I were planning to hike much, I’d probably get a more sturdy pair of Teva’s or Chacos with a strap around the back instead.
Two pairs. One should be a walking shoe/ tennis shoe. If you are going to go to a fancy restaurant, then do a non-white tennis shoe so you’re covered. Likewise, for the second pair, do a waterproof sandal like a pair of Tevas. Honestly, I have never understood the use of flip-flops or watershoes as they are far too limited. If you wear Tevas, or other velcro waterproof sandal, you can walk to the beach in them, go in the water with them, and even do some light hiking or rock scaling with them. Flip flops and watershoes don’t have enough grip or thickness to them. Besides, with all the limitations on baggage weight and available space, I’d rather pack extra shirts/shorts/socks/underwear for the inevitable stains or other issues that arise. Shoes are too bulky and heavy to bring a lot, and with my strategy, you only have to pack one pair because you wear the other on the plane.
Rubber thongs, blingy thongs, walking boots.
(Can’t tell you how much I hate the term ‘flip flops’. They’re thongs, people, THONGS!)
Flipflops all the way. I’ve got toddlers, so there’s no need for anything studier for hiking, and we wouldn’t be getting into any water that required water shoes or going to a restaurant that required nicer shoes. Also, I wouldn’t need my golf shoes, or any walking shoes for walking around town.
On second thoughts, we could ditch the kids and take the shoes.
This. Waterproof sandals, fancy sandals and walking shoes. And I’d wear the hiking boots/sneakers on the plane, so technically, they wouldn’t be packed. 
Same here.
I’m not sure, but it would definitely be an even number.
I usually take flip flops, a pair of nice shoes, and sneakers. They don’t take up a whole lot of space in a suitcase, especially since you’ll only have to pack two of them and wear the leftover pair. If you can find sandals that are comfortable AND pretty, they can do double duty. (I’m speaking as a woman; I dunno if this would work for men.)
The shoes that really give me a headache are my hiking shoes. They are much heavier and bulkier than all my other shoes.
4 at a minimum. I’d probably have a couple more depending on my outfits as well. I like my feet to look good.
Always have a second pair to change into if the first pair gets too wet to be comfortable or if you are hiking and have given yourself a blister or two. Or, you could always plan to buy a pair after you arrive…
Flip flops and a pair of sneaks
I have a pair of water shoes that I wear practically everywhere. They are like Tevas or Chacos, but a different brand (Kamik). They are good for walking around, and for going in the water. I bought them originally for a kayak trip where we would be in and out of the kayaks several times during the trip, and doing some trail hiking on rocky terrain. I would take them to wear everywhere but dinner. I would take one nice pair of dressy sandal/thong type shoe that matched all dinner outfits.
Two: my Merrell hiking shoes and my Sketchers sandals.
Two: if mountains will be involved, walking boots (selected for “wearability in hot muggy weather”) and a pair of sandals or espadrilles chosen for walkability. Alternatively, if no mountain areas would be involved, two pairs of sandals or espadrilles chosen for walkability.