Hi L.!!
I always try to plan as much as I can online. Then, some things, are really better talking to someone, so I will actually pick up the phone and call.
One website that I use A LOT is www.allearsnet.com. I love the disney website as well. However, sometimes all of the animation and flash presentations tend to make it slow some times when trying to find the info that I need. I prefer to use allears for almost everything. They have a searchable tip database. You can sign up for a weekly newsletter (email) and there is also a yahoogroup associated with the site. I found it most helpful in the planning process. Though it is mostly disney information, there are people that ask about other Orlando area activities. I know there are have been several discussions about that on the yahoogroup. As a subscriber to allear's newsletter, you can get special discounts on Disney specific travel agents, etc.
I like to actually pick up the phone if I want something REALLY specific that cannot be conveyed over the internet. I use the Dining phone line to schedule my Advance Dining Reservations (Reservations for restaurants at WDW that I definitely want to eat at). I know they have recently gone online for that, but I still like to talk to someone and think that it is easier for them to check through their system (and faster) than I can fumble through online.
My personal opinion, if you like the ease of 1 stop shopping than a travel agent that specializes in WDW vactions may be great. However, if you are looking to make sure you get the best deal and pay the best and most fair price of things, I would definitely shop around. I personally tend to shop around. I feel I get the best deals that way. We are going in January (my personal favorite time to go) and we got airfare from NE Ohio for $150/person. We are renting points from a DVC owner and paying $100/night LESS then for a regular room at the resort. I have learned all of the things by lurking around the various websites and disney boards.
If you need any additional suggestions or help, please let me know. I love helping people plan things - especially when it is their vacation to the most magical place on earth.
Happy planning.
K. O