Tripadvisor and websites. Google Maps is a big help determining the suitability of neighbourhoods and route-planning.
My criteria for choosing a hotel was:
1. That my hotel be small, less than 50 rooms. I don't do North-American-style hotels when I travel. Well, I guess I do when I'm in North America. Anyway - a pension-style hotel with a breakfast room is all I need.
2. That it be within easy walking distance of the Île de la Cité. Although I've got a wheelie-bag and good walking shoes I wanted to be less than a mile from Notre Dame. For easier figuring I took a reading from Saint-Michel RER stop. 1 mile = 1.6 km
3. That it be less than $250 Canadian per night. Today (March 31, 2011) $250 CA = 182 Euros.
4. That it received good reviews on Tripadvisor.
5. That the bedroom consist of non-IKEA-style furniture.
Regarding Tripadvisor, it's a good tool. I don't hold too much with other people's reviews because everyone's got their own set of criteria. But every picture's worth a thousand words. I know right away by checking out reviewer's hotel pictures if it's the right place for me.
On a general note, the hotel had to look like it would make me feel secure and comfortable returning to it after a long day.
I pared my list of 45 down to a final 8. Here are the finalists.
1. Hotel des Grandes Ecole
1.3 km from Saint-Michel RER stop.
This lovely pink and toile hotel is set in its own sizeable garden off the Rue Cardinal Lemoine. Charm at reasonable prices. I've wanted to stay there since 1992. Now I can afford it, they didn't return my email. It's so popular that they tell you when to attempt a reservation, (4 months in advance). I'm not staying here. http://www.france-hotel-guide.com/h75005ecoles.htm
2. Hotel des Grand Hommes
1.1 km from Saint-Michel RER stop
Amazing location overlooking the Paris Pantheon. Beautifully decorated and larger bathrooms than most hotels. Would not accept a reservation request through personal email. They wanted me to use the automated booking which frankly I don't trust. http://www.hoteldesgrandshommes.com/
3. Hotel du Pantheon
1.1 km from St. Michel RER stop
Located next door to its sister hotel, the Hotel des Grand Hommes. It's gorgeous too. This is where I ended up staying. I couldn't recommend it enough. My room and my view was superbe. http://www.hoteldupantheon.com/
4. Hotel Britannique
600 m from Saint-Michel RER stop
So close to the Louvre and the Seine, the Hotel Brittanique, located at 20 Avenue Victoria, originally appealed to me because of its history of being run by English-speakers. http://www.hotel-britannique.fr/index.html
5. Hotel Beaubourg
1.2 km from Saint-Michel RER stop
The Beaubourg appealed to me because of its funky furnishings and its claim of a garden. It's on a small side street that empties out at the Centre Pompidou. http://www.beaubourg-paris-hotel.com/index.html
6. Hotel Henri IV Rive Gauche
.3km from Saint-Michel RER stop
The side-street rooms at the Hotel Henri IV Rive Gauche have amazing views of the Église Saint-Séverin. http://www.henri-paris-hotel.com/
7. Hotel Caron de Beaumarchais
1.3 km from Saint-Michel RER stop
The small rooms at this equally small hotel, located in the Marais, look absolutely charming. http://www.carondebeaumarchais.com/
8. Hotel de Lutece
1.3 km from Saint-Michel RER stop
Located on the Ile Saint.-Louis, (to quote Liz Lemon "I want to go to there"), the Hotel de Lutuce is a one minute walk to Berthillon, where I intend on having an ice cream. http://www.paris-hotel-lutece.com/
I did almost as much research in 2003 when I went with my family and the Hotel du College de France put us in a small "courtyard" room on the 1st floor overlooking the kitchen and the laundry room. You just never know!