Our Hotel Options...

These are the hotels we're considering (Mind you, we're looking for relatively budget places, nothing that will set us back too many Euros, considering we will not be spending the bulk of our time in the hotel. We plan on doing a good amount of sightseeing, some R&R, and living la dolce vita!):

Sorrento:
Hotel Loreley et Londres - This hotel is perched on the cliffs, if I am viewing the pictures correctly. Not much information available online, hence the lower prices. It's a 2-star hotel, among 4-star properties, offering views of the coast. (Open March-September)
Hotel Mignon Meuble' - Hotel in Sorrento town center.
Casa Astarita B&B - B&B located in Sorrento town center. They have a website, but I can't read the grey print against the orange.
Il Palazzo Starace B&B - B&B located in Sorrento town center.
Hotel Nice - Hotel in city center.
Residenza Maresca - Private room in Sorrento

Lodging Options Outside of Sorrento:
Casa di Campagna - B&B in nearby Sant'Agnello. www.casadicampagnabb.com
Mami Camilla - B&B in Sant'Agnello. You can enroll in cooking classes. www.mamicamilla.com

Also, visit:
- Port of Napoli Website www.portanapoli.com (it even has links to convent availability; sights in Naples and Campania; recipes; and much more)
- Sorrento Online www.sorrento-online.com (info about Sorrento, including hotels, sights, etc.)
-Sorrento Tourism www.sorrentotourism.com (I researched a lot of lodging options at this site.)

Perugia: The website www.perugiaonline.com is quite helpful. It has listing of all types of loding in Perugia, including hotels, B&B, apartments, convents, and also links to towns in Umbria.

From that site, we're considering:
Hotel Sant'Ercolano www.santercolano.com (Currently offering winter specials!)
Hotel Europa www.hoteleuropa-pg.com
Hotel San Sebastiano www.hotelsansebastiano.it
Hotel Umbria
Hotel Ilgo (according to website, 1km from town center) www.hotelilgo.com
Etruscan Chocohotel www.chocohotel.it (Chocolate themed hotel in THE chocolate capital of Italy)
B&B Spagnoli www.perugiaonline.com/bbspagnoli/
B&B Alla Residenza Domus Minervae www.domusminervae.it (Classes and lodging combo)
Residenza Baldesca (apt.) www.perugiaonline.com/residenzabaldesca/
Residenza Turrena (apt.) www.perugiaonline.com/residenzaturrena/

I've also come across another apartment via searches on VRBO's site:
This apartment is supposedly near Corso Vannucci, the heart of medieval Perugia, and would be a good option. It would be 395 Euros/week. http://www.vrbo.com/70586

Another private home site to browse is http://www.homelidays.com
But they didn't have any listings for Perugia - in the city center. Maybe in a few months or so! Keep checking.

Last, but not least, check out Slow Trav's reviews on Italy's rentals.
Siena: Visit http://www.turismoverde.com and compare hotel's prices in Siena.
These are some we're considering in Siena:
Cannon d'Oro www.cannondoro.com - I have stayed here twice (once with my sister and another time when we toured with Rick Steves). The first time was in winter, so not many tourists and I really appreciated the central location. The second time, I just remember the THIN walls and how noisy it was (this was during the summer).
Albergo Bernini www.albergobernini.com

Milan: Here's our list so far:
Aspromonte (2008 Update: my sis and I stayed here and we're not that impressed. While the staff was really friendly; the hotel was not as close to the metro as I would have liked and it was a little far away from the city center. Another thing that turned me off is that this hotel, although it was spacious like reviews read ... I just smelled cigarette smoke the entire night. Ugh. I forget but I think we found a hotel that is centrally located in Milan and somewhat affordable!)
Eurohotel www.eurohotelmilano.it (First link is the hotel listing on venere.com; second link is the hotel's website.)
Monopole (I stayed here last time. It was fine; right near the train station. The reviews are mediocre on venere.com, but we found it to be a very nice establishment.)
B&B Milan
Gambara

Hotel Resources:
http://www.venere.com
http://www.guestinitaly.com
http://www.initaly.com

Plus, there are countless B&B, apartment and villa rental agencies at one's disposal. Check out Slow Travel's website (http://www.slowtrav.com).