you have to consider what you want.
Kissimmee is closer to WDW than anything - has some very nice places to stay - I would suggest American Suites/La Quinta
when are you going if soon then
www.priceline.com
if you don't anything about this site then go look here
www.biddingfortravel.com
now if you aren't leaving soon - priceline is best down at the last minute
then go try
www.hotelkingdom.com
they have some good rates
if you find a hotel that you like - then before you make the reservation come back here for feedback
here is a site for Kissimmee
http://www.floridakiss.com/
you want the vacation planning kit - it is free
then you need to decide where you want to be close too - if WDW then this guide is great - tells you were all the hotels/motels - some condo and timeshares in the Kissimee area are located.
but I would still go with online service for making the reservations - why - they can be cheaper - but always look at the hotels website too - they can be cheaper themselves....
www.choicehotels.com