The tip from me would be to be flexible because you are not going to know how the toddler will react to WDW until you are there. They can really surprise you! How old is the toddler?
DD was 2 years 10 months when we took her for the first time. We did 2 days MK, 1 day EPCOT, 1 day AK and 1 day DHS. We had hoppers, but that is just a personal choice for WDW- we like them. We found that our 2 year old absolutely hated AK- all she did was keep begging to go back to MK or EPCOT, so we did use our hoppers. We gave up AK about 1:00 p.m., and then went to MK. Basically, for her, she looked around and there were no Princesses at AK, not that many rides for her age, it can feel hotter than the other parks; and we have a really good zoo at home which she had been to multiple times, so she had no interest in seeing animals. So, that was a surprise. We thought she would like all the parks. It took a few years before she started to somewhat like AK, and it is still her least favorite park. It turned out we spent from open to close in EPCOT, but did not have enough time. She loved it there. So many little things for a toddler to explore. So many Princesses. The boat ride in Mexico, Nemo ride; Kidcot stations; Figment; play areas etc. (Never underestimate how impressive the Living with the Land ride might be to a 2 year old. The greenhouses were a huge hit.) We needed an extra day there. When she was 3, we spent 2 days at EPCOT-- and it has been a 2 day park about every trip since then.
As far as park breaks/naps, I would tell them again to follow their child's cues. The park break did not work for us at all. All we got was a very angry 2 year old who stood behind the curtain in the room for 2 or 3 hours pouting refusing to nap because we had made her leave the park. When we went back to MK, she promptly smiled, climbed into her stroller; and went to sleep for over an hour. After that, it was park naps in the stroller for us. That worked great for her as a toddler. So, we basically just stayed in the parks from open to close, and she just took naps or slept in the stroller when she was tired, which gave DH and I the opportunity to take turns riding some of the thrill rides while she was sleeping. For us, what worked was scheduling a TS lunch. Pre-park opening breakfasts were a disaster because DD has never been a morning person. At dinner, if she was getting tired from the day, she was fidgety. Lunch was perfect, because gave us a nice break from the morning, got our energy back up to keep going; and wound her down so that we could get her to nap in her stroller pretty much right after lunch. That may not work for everyone though. DD has always been a high energy child. She thrived on the Disney excitement and loved the characters as a toddler. Other kids are different- so I think you just have to see how your child reacts when you are there and adjust accordingly.