I thought about it for a while over dinner. If I'm travelling alone, a hostel bed will do, although a single room is preferable. I spend a minimal amount of time in the room anyway, so I don't find it useful to spend more money than required for a secure, clean room and bed. I've rejected places that haven't had one or another. One memorable guesthouse in Vientiane was a breeding ground for mosquitoes--bad news in a place with multi-drug resistant malaria--and I got out of there fast. For me, in hot climates, air-conditioning is not optional.
Food, on the other hand, is something I'm going to savor as I eat it, remember afterwards, and greatly influence what I think of a place in general. It's important to me, and I'm willing to pay for it. On the other hand, a cheap, unpretentious hole in the wall with zero decor but great food is just fine. As Tsui said to me recently as we were eating in an open-air dessert place in Bukit Timah, just up the road from his place, "The great thing about hawker centres is that someone might drive up in a Rolls and order something to eat. Sometimes, the best food really is in the hawker centre." (Just then, he pointed over my shoulder. I turned to see someone pulling up in a Jag.)
It is probably why I'm so fond of Singapore and Penang, and why I think Sao Paulo and Johannesburg are undeserving of their awful reputations.
If I'm travelling with someone I'm sleeping with (i.e., having sex, not just sharing a bed), that's a different story, although once we've got a big bed in a room of our own there really isn't that much more I require. I've paid for a jacuzzi, and think that's definitely worthwhile and great fun, and a bidet in an attached bathroom is nice, but clearly not essential. A verandah one has one's breakfast served on is also a nice touch, but again, not essential.
I'm reminded of a place in Paris that had a bidet in the attached bath, a nice big bed, breakfast brought up to our room on a tray, and staff that were clearly pleased--in what seemed like a very "Paris in the springtime" way--to have a young couple staying in one of their rooms.
I guess what it boils down to is that food, sleep, and sex (as I said in my original introduction) are my three great pleasures in life, and my sleep requirements are relatively few. Food, there's endless variety in. Sex, there's also endless variety in, but the bed's just a venue; the performers and the action are much more important to me than the stage.