If my units have just taken a city by military force, how can I view the city screen before making the critical decision - whether or not to raze it? I mean, my troops are standing right there in the city streets, so can't I at least check out the existing buildings, etc. before making this decision?
(Civ IV - Vanilla)

You pretty much have to make that decision before you attack. You can tell whether or not the city is a holy city by the icons under its name. Wonders and other buildings will be visible in 3D on the map, but you have to look closely. Other than that, there is no way to get detailed info before Communism. At that point you can build Scotland Yard and send up to 4 spies to scout out the cities before you attack.

The info screen (F9) shows every Wonder a civilization owns. For five cities, if you know where they are, you can see every Wonder. For other Wonders, you will have to look for graphics clues. Holly cities are easy to see and the info screen shows every shrine built. Only later in the game you can build a spy. If you let it inside a city, you can see everything: the buildings, the production, etc. You can have only three spies.

save/load if you ask me... though normally you'd raze a city because:

a. it's in a bad position; so... no matter what it holds in there, it'll still be in a crappy position 1M years later...
b. you can't afford it; usually, when you can't afford it, there isn't much the city could contain in order to make it affordable(we're talking bcs probably, and in bcs there are few buildings you could capture to start with).

so, all in all, 'xcept wonders, probably what's in won't make a diff. on your decission.

wonders -> f9 -> top5 cities -> scroll through the wonder list and see if it's anything in there; or zoom in.

buildings - zoom in again; pity you won't know what will survive after you take the city, so abit of a gamble(all cultural buildings get razed on capture, so it leaves the rest)