I've been to all those areas, though travelling backpacker-style rather than rented 4WD so my budget was probably "slightly" smaller Didnt have any problem w finding accommodation in El Chalten or Puerto Natales - this was December 2003 - but then I was staying in hostels. Torres del Paine is surely where it is difficult to find hotel rooms, I slept in my tent and in Refugio Chileno which at that time (1999) was brand new.
Photography at Torres del Paine, sunrise seems to be the key. Weather changes fast, I'm sure you know about that. I didnt hike up to Mirador Las Torres for dawn, it's a long hike. The good thing is you get a majestic view of the three pillars facing southeast, so it is good for sunrise. The hike from Refugio Chileno was over two hours, moderately difficult. Bring a flashlight/headlight, as you have to start out from Refugio Chileno when it is still pitch dark (4AM).
Otherwise, the reflections in the lakes south of the mountains at dawn can be fantastic. Afternoon weather is often cloudy so use the mornings well.
I took the boat from Pudeto over Lago Pehoe to get to the trailhead round the massif. It was just drop-in but this was nine years ago, there are a lot more tourists there now.
Here is a decent overview map: http://www.torresdelpaine.com/ingles.../a/popup/3.htm
Notice how the lakes are close to the mountains - the key is to get to the other side of the lake to get a good reflection - and hope for no wind.
Glaciar Grey can be photogenic up close, but not so much from a distance. it's a long hike from the trailhead. Id' say it's not worth it if you are limited in time.
El Calafate: The town itself is pretty boring and far from the mountains, the real attraction is Perito Moreno. I camped about 5 km from Perito Moreno, to get there at sunrise. No interesting hikes around town.
Here is a link to my travel journal from the 1999 trip, and some photos. The journal is not complete, I lost some pages for that week. http://www.vinberg.nu/pages/1999-01-...stopuerton.htm
As you can probably see from my photos, the best light at Perito Moreno is at dawn and early morning. The sun reflects in the lake, lighting up the side of the glacier in a spectacular way. Also notice the afternoon shots from where I camped, the view back to the glacier is not bad, especially with loose ice drifting in the lake. You'll recognize the place as you drive by, the water is about 400 meters from the road as far as I recall.
El Chalten... I went there in 2003. Your best friends are ND grads and factor 50 sunblock. Once again, the best light is at dawn and early morning. Once the morning sun hits the peaks at full strength, the contrast level is incredible. Even if you have a sunlit foreground it will be 5-8 stops down from the peaks. Bring ND grads, lots of them. I have 1-2-3 stops, both soft and hard. You'll be in better shape shooting digital so you can review the results on location, I was shooting 6x12 and 4x5 slide film and looking back I'm not happy with the results.
My journal notes from 2003 (no pics): http://www.vinberg.nu/pages/2003-11-23.htm
Here are some pics from my weeks in Patagonia in 2003. Only one from Chalten, and I have to admit it looks a bit edited. http://www.8x10.se/pages/collectiongallery.asp?id=12
Finally, a place you are not going to and a bit hard to get to (airplane, car, hiking, boat, and finally waders): These are caves, in blue-white marble, sculptured by ice. http://www.8x10.se/pages/collectiongallery.asp?id=21
Hope this helps,