I would rather stay longer in a less expensive resort than to go or a shorter time period. There is so much to do. Especially for first timers.
But if I was planning a later trip with DH, I'd consider a short trip this time..... and saving some stuff for when DH can go.
We have been to Disney World twice, the first time for 8 days, and the last time 9 days. It's just impossible to do it ALL in even that amount of time. And we were there during a non-busy time of year which means we get more done in the same amount of time compared to someone going during a busy time.
Since you will be by yourself as the only adult...if you can afford it....I personally like the monorail resorts (Polynesian, Contemporary, Grand Floridian) because you can get to places very quickly and lots of restaurants with easy access. And Magic Kingdom is a very quick monorail trip or boat ride. It also saves time... and there's always cheaper rooms (Garden View) at these resorts and lots of specials (room discount, possibly free dining) that will be offered soon or now depending on when you go.
My favorite for children is the Polynesian for the transportation choices and the theming. You can quickly walk to get the monorail from the main building, and to the transportation and ticket center to get Ferry boats to Magic Kingdom and the monorail that goes directly to Epcot. There's also a boat that goes straight to Magic Kingdom and circles back to the Grand Floridian and back to the Polynesian. You can see the castle and Magic Kingdom fireworks from the Polynesian's volcano pool and beach overlooking the 7 Seas Lagoon. At night, all the paths are lit with tiki torches.
I'm almost persuaded to change my next trip to stay at the Poly again!