THe telephoto zoom lens with a VR (vibration reduction is something to behold.
You can be into a package for less than 1,300 with a zoom lens that is equivent to 35mm's field of view of 36mm-210mm (wide to telephoto). You won't probably use a different lens unless you need a macro lens for very close-ups, Peggy. I'd get two filters - a UV and polarizing ring filter for that trip.
You'll need a small case to hold the camera, charger for the batteries, etc.
You might also consider a digital flash -- but that's another $250 bucks (Don't unless you really want to take a bunch of group or other indoor pictures.) The VR lens really helps with the handheld functions.
http://www.ritzcamera.com/product/RI541532941.htm?utm_medium=GAN&utm_source=google
http://www.amazon.com/Nikon-D90-Digital-18-105mm-3-5-5-6G/dp/B001ENOZY4
Reviews:
http://www.kenrockwell.com/nikon/d90.htm
http://www.dpreview.com/reviews/nikond90/