We took our (then) 18-month-old to Disney a few years ago. After a great deal of consideration and advice seeking, we got a small suite at the Dolphin. This cost about the same as a room on the monorail but provided a few upsides:
1. If you are bringing a toddler and no other children, you're really on an adult's vacation. You won't need to spend 75% of your vacation in the Magic Kingdom, so monorail access at the hotel isn't as important as it was to us when we took her at age 3, when we spent much more time within sight of the Castle.
2. Good room service. Restaurants were not always in the cards with our little one at this age. For dining out, you have lots of selection in the Swan and Dolphin, the crescent lake resorts, Epcot and MGM relatively close by. This flexibility really suits a vacation that requires changes in plans.
3. A small suite at the Dolphin or Swan is about the same cost as a room at the GF. We had enough space for our little girl to play and roam in our room.
4. Have you ever slept on a "Heavenly Bed"? You should. They have cribs, but our little one liked falling asleep on the second bed in our room. I don't know if they have rails, but our daughter was a sound sleeper who could sleep on a bed without them at that age. Either way, the bed you sleep in will be spectacular.
5. A quiet, lonely kiddie pool, even during a peak week near Easter. This is a business person's hotel. Kid decompression can be a good thing.