I can recommend a hotel, sarah. I was in Paris a couple of years ago by myself and stayed here:
http://www.hotel-royalphare-paris.com/
I just sent some other folks there, and they were pleased, too. It's a fairly typical small hotel (TINY elevator!), but it's reasonably priced and clean and you can't beat the location. It's within walking distance of the Eiffel Tower, and there's an ATM, a local market, a patisserie and a Metro stop just outside the front door.
Notre Dame is good, but don't miss Ste. Chappelle. It's a few blocks away, next to the former palace (Ministry of Justice now.) It was the private chapel of the French royalty and is considered the most exquisite church in France. I believe it.
Also...the restaurants are very expensive in the evenings. I ate great lunches there instead, then picked up fresh bread, olives, cheeses & wine and ate picnic-style on the lawn in front of the Eiffel Tower each night. The lawn fills up with people to watch the sunset and the lights come up on the Tower. People bring guitars, birthday cakes, everything. It's like a giant celebration every night. Then after it's dark, walk under the Tower to the old-fashioned carousel and enjoy some ice cream while you watch the boats going up and down the Seine. Paris doesn't get any better than that.
Oh! Red double-decker buses in front of the Tower during the daytime offer good sightseeing tours. You can get off at any of the stops, spend as much time as you like, then get back on. There's another bus about every 15 minutes or so.