This is about half speculation, but I'll add it anyway.
I sync my MobileMe address book , and I noticed that my custom labels show up on the phone. That means that instead of a phone being labeled as work, home, or mobile I can add my own labels like; billing, support, or Jimmy Dean.
Of course I can't edit these on the phone {correction, you can create custom labels on the phone. Must have been added recently, because I tried this before. }, but I wondered. If they get synced then Google Contacts must have this ability.
Sure enough, you can create custom labels in Contacts on Google. I suspect, but would not bet my life, that they will show up on the phone when synced.
So, if you are syncing with Google, go into your contacts and create custom labels for each phone number. At first I was afraid this would create a long list of custom labels, but apparently not. None of the custom labels I created showed up on the pull down menu.
A lot of work for 1000 contacts, I know. But at least it is something you can do. If the letters are still at the end of the numbers you could save a bit of time with cut and paste.
Come to think of it, you might be able to change these in the spreadsheet too. Make a couple custom labels, export the address book, and see what they look like.
Good luck.