Need Help Lense Recommendation
 

After doing a bit of research I have narrowed down to 2 lenses to choose from Canon EF 70-200mm F/4L USM or the Canon EF 70-300mm F/4-5.6 IS USM. Both is around my budget of $800. Currently I have Canon EF-S 18-55mm f/3.5-5.6 IS lense that came with the camera. My preference would be to able probably zoom in and take pics from a distance,moving objects,monumental structures/buildings, general everyday pics with family friends etc, and maybe close up or I can just use the EF-S 18-55mm f/3.5-5.6 IS lens or I can go for the Canon EF 24-70mm F/2.8L USM later on. I am just wondering which lens out of the two would provided suit my usage. Also I was just wondering if the Image Stabilizer should be an must have function. Btw I have the Rebel XSI and this is actually my first DSLR.

for structures..consider the tokina 11-17 wide angle
everyday..the 24-70mm L is super sharp..if u dont plan to do fullframe upgrade..17-55mm f2.8 IS from canon is good

for the zoom..get the F4L