Which lens to buy for my Nikon D90?

I take pictures of pretty much everything from senior pictures, to travel photos, etc. My current set up is a Nikon D90 with a Tamron 18-200mm lens. My next lens I plan on spending a little more money. They two lenses I'm stuck between are the Nikon 70-200mm 2.8 and the 24-70mm 2.8

Any advice would be great

Neither choice is optimal given what you have and the pics you take. 18-200 goes from wide angle to long telephoto and should be great overall. The 24-70 mm is great for a Nikon with a full-size sensor such as the D3 but not for yours: 24 becomes 46 mm in 35mm terms, which is standard angle while 70 becomes 100 mm which is moderate telephoto.

If you really want to splurge and you need the wider aperture, 10-20 mm 2.8 or f/4 and 18-70 or 18-100. You keep your telephoto zoom to reach 200mm.

I don't see anything wrong with using a 24-70mm lens on crop frame, i like to use that focal length range very much as well (albeit not on a $1500 lens as of now). The image quality of that zoom lens is said to be stellar though, rivalling many primes. But it's big and bulky. Really big and bulky. On that site you can see it dwarfing a D3:
http://www.kenrockwell.com/...4-70mm.htm

@lolvark: It's be 36mm to 105mm full frame equivalent,
The 24mm end of that lens is reasonably close to the 18mm of a crop sensor standard zoom (18-55mm), and far wider than crop sensor normal view (35mm)

Well, which one will be better for you will depend on your focal length preferences. Take a look at what focal lengths you mostly use, and choose to accommodate that. You may find the need to change lenses to be quite annoying though, being used to a single lens solution.