I've been saving this post until the end of the initial planning stage for one very particular reason - it encompasses all aspects of the initial planning phase, booking, dining, and transportation.
I'm not a fan of staying off-site. There are way too many perks to on-site guests (which I'll get to shortly). It drives me nuts when people say they stay off-site because it's cheaper. That couldn't be further from the truth! Yes, your actual hotel stay might be cheaper, but the benefits to staying on-site save you so much money, it all works out in the wash. Most people only see the initial costs and don't factor in all the little expenses that occur once you get there, which leads me to these infamous benefits I keep mentioning.
You can safely assume that ticket prices and your meals will be cheaper if you get a resort package, simply because Magic Your Way Packages and dining plans aren't available to non-resort guests (although you can book dining reservations, just not at the 180 plus 10 window that I mentioned before). But it's all the other perks that make it worthwhile.
First up, free parking for resort guests. Parking costs are $14 per day, a 7 night trip, which is 8 days of park time, makes a total of $112 for parking alone! If you haven't driven your own vehicle, then odds are if you're paying parking fees, then you've rented a car. Car rental fees alone are enough to make up the difference in cost for the resorts. Then you have gas, which is always expensive in vacation spots, as well as the fact that most all the major thoroughfares in Orlando are toll roads, and I've just answered my argument!
Automobiles bring up yet another costly topic...time. The time you spend from your hotel on to property and then to the parks is enormous. And oh, the traffic! Let's just say you are not going back to your hotel for lunch or an afternoon nap.
Disney transportation is only for resort guests (although they don't strictly enforce it, like I mentioned before, I have seen people get turned away for not having a resort ID). Besides, riding buses are stressful enough, it makes them down-right murder when they are filled with non-resort guests who shouldn't get the perk and you're either crowded in or forced to wait for the next bus because of it.
Next up, extra magic hours...resort guests get either an extra hour in the morning or an extra three hours in the evening (about to be knocked down to two) in selected parks on selected days. So while the general population is performing a mass exodus from the park, you're still in line for the Haunted Mansion! EMH is one of the best perks for entertainment value! I've seen it play out a hundred times, there is always a non-resort guest demanding to stay in the parks and causing a scene - it's hilarious! At first, Disney set up barricades where you can't get into certain parts of the park without the EMH wristband (which is where most of the non-resort guests get caught) and then, once they are assured the masses have cleared, they really only check it when you're trying to get on rides, but by that point, all the non-resort guests have gone. In Animal Kingdom, three extra hours is the only time you'll ever be able to see the park in darkness, or for Magic Kingdom or Epcot, be there into the next day!
My most favorite perk, package delivery service! We buy a lot of stuff in Disney, in the parks, the stores, other resorts other than our own, and if we had to carry all of it around, our days would be short. But resort guests can have their purchases delivered directly to their resort gift shop the next day (or directly to the park entrance the same day). Oh what a blessing this is! Although the resort gift shop CM's (Cast Members are the official name of Disney employees), might disagree - by the end of our trip, they run like cockroaches in the daylight when they see us coming because of the quantity of packages they have to dig out!
Speaking of shopping, resort guests can also use their room card/park ticket (called a Keys To The World Card) to charge purchases back to their resort...it could be your purchases in a store or even your meal, anything you can purchase, you can charge provided you've allowed charging privileges. Different resort levels also determine how much a day you can charge, with the deluxes (of course) providing the highest level of charging.
There are times when the parks fill up to capacity and have to close. For those still outside waiting to get in, that's a royal pain. But resort guests (although not guaranteed entrance into the park they are in line for) are granted admission to "a" park, whether they have a hopper or not. Non-resort guests are just stuck out.
There are other perks, least of which is being immersed in Disney magic 24/7 or having the quality of service that Disney provides. Only Disney guarantees magic and only they can deliver it. Disney goes above and beyond in every aspect, and like I always say, "if you have a bad time at Disney, it's more than likely your fault and not theirs!".
Once you've booked, scheduling your days comes into play next, because you can't make your dining ressies without it! But that's a post for another day!