First of all different species have different shapes. Some will normally be very upright, while others normally flat.

Secondly, the poor Echeverias in your second photo look fried (burned or overheated) and wilting in response.

Hydration, too, can make things perk up or wilt depending upon if well hydrated or not...

I know - I'm not sure what had happened to those poor echeveria. I think that maybe I had watered them but forgot to remove the retaining dish, and so the leaves rotted a bit? But that was a while ago and I am happy to report that they are now not only fully recuperated, but reproducing as well.

{{gwi:619117}}

(in this photo they are now tight little balls)

I guess my question was mainly, what situations make them more likely to flatten out (warmth, hydration) and what situations make them ball up (cold, dehydration?).

They will flatten out to expose themselves to more sunlight, to get more light to the central growth core. (Agaves it is really easy to see this) They curl up to reduce transpiration (loss of moisture) and to reduce their sunlight exposure. (Aloe peglarae is a good example of this) This is one of the marvelous things about succulent plants--you would think they are static, but if you look at them day after day you can see the changes and adjustments they make. They are quite marvelously alive and dynamic.

My echeveria "Lola" (my favorite of them) did the same thing just recently. It had been flat like I had seen in a magazine when I purchased it, and now, two months later, it's "pinked" in color and the leaves are cupped like yours. Absolutely nothing changed in terms of temp, sun, watering. Hmmm......Oh, well, they're beautiful both ways!!

thanks - so interesting! i love succulents so...