For outside shots, you definitely want a solid zoom. Something up to 200 will work pretty well, but I find I use a 300 fairly often to get some of the neater details in the higher-up areas of buildings. Understand that while fast lenses ROCK, you can give up some of this (to save money) in most circumstances since you will be outside and will generally have better light than you will have indoors.
Just keep in mind!!! The longer the focal length, the faster your exposures will need to be to avoid camera shake. I've seen a few guides but you have to figure at
least some percentage over the focal length of the lens... if you're at 300, figure at least 1/400th of a second. That means you're going to need good light to get that shot.
Note that you are likely going to occasionally want a wide angle lens for the exteriors, but if you are doing more artistic shots you're going to want the close-ups more frequently than the wide angle.
For interior shots you're going to want the speedier lens whenever possible, because no matter how good the light may seem to the human eye, I can almost assure you that interior light is going to be too dim for a good/easy shot.
For most interiors you will find you want a wide angle lens... generally this depends on what you are shooting... you can probably get away with a 30mm ish size in a cathedral or church, but my general advice here is the wider the better. 18mm or less is really the way to go here. Understand that if you are taking pictures of smaller spaces (like even 20' by 20' rooms) that wide angle gets critical. Again, if you are taking more artistic pictures, my guess is you will be zooming in more and the wide angle may become a bit less of a concern. Keep in mind that there are wide angle zoom lenses, but getting a FAST zoom lense (f2.8 or less) can get really expensive quickly (and that's if there is one that meets your needs).
Last point on the wide angle lenses... the full/partial frame debate is one that rages on constantly, but there is one undeniable problem with the partial frame, and that is that it severely limits how wide your wide angle lenses are. The 18mm I use all the time really winds up being more of a 27mm. In tight spaces this hurts a LOT. Be aware of what your camera does before choosing a lens as it may make a big difference in your choices. (If you're not using digital, this is a non-issue, obviously)
I would strongly recommend making sure you have a tripod with you as much as possible. Sometimes this can be a huge pain but it significantly reduces problems with light and long focal length. It is not a panacea, but it helps enormously. Keep in mind that not everyplace is going to relish you taking pictures, not to mention setting up big tripods!
My latest experiment is going to be using some mini-tripods just to see how this works out. Quick setup/breakdown and not nearly as obvious as some big thing. We'll see.
I hope this helps! Good luck!
. Would you know if a zoom and a wide angle lens are two separate purchases I'd have to make? Or are they together? I just need some info before I walk into 
