The Touch HD does not have US 3g bands. Good luck surfing on EDGE!
HTC Touch Diamond 2 is pretty similar screen size plus US 3g and probably available subsidized thru the carriers. HTC Touch Pro 2 has similar screen size, plus slide out qwerty and brings back the tilting screen from the Tilt.
Otherwise if you want to go unlocked and Symbian the Nokia N97 brings will be similar slide/tilt qwerty touchscreen like the Touch Pro 2, and the Samsung OmniaHD is a similarly-spec'ed touchscreen-only phone.
I have a Tilt and I use the following apps to make it more appealing:
Google Maps - general mapping and location-based search
Live Search Mobile - like Google Maps but also does turn-by-turn navi and location-based gas prices (I used on Saturday when my gas light came on while driving from Chicago to Madison)
Opera Mobile - good browser for actually loading HTML
Skyfire - alternate browser, does Flash etc
Fring - IM & Skype client
Youtube
WM Internet Connection Sharing cab file - the unlocked HTC tethering app, better than AT&T crapware
WMwifirouter - turns the phone's data connection into a wifi hotspot (used this my whole vacation in Vegas when I didn't want to pay for the hotel's wifi)
PicoDrive - Sega Genesis emulator
Personally even though Windows Mobile is clunky, no other OS offers every single one of these options so I'm keeping my Tilt.