We've been going to the park annually (from Texas) for the past 15 years. Up until the last year all our trips have always been 2 weeks long. A few times we took a 2 day side trip over the weekend but the majority of all those trips most of the entire 14 days of each vacation were spent inside the park.
While many folks thought us crazy for spending so much time in one place we loved the extended stays and really appreciated the leisurely pace it allowed us to enjoy. My bunch are not earlier risers so having the abundance of days meant we did not have to be at the park at opening unless we wanted to be. We could stay all day if we wanted or could just call it a day early if we were tired.
There has never been a need to worry about not having enough time to see all the attractions or ride all the rides. We are huge fans of riding the same rides over and over anyway so it works well for us.
There were plenty of mealtimes so we have enjoyed being able to try just about every eating place in and around the park.
Time and finances have reduced the length of out vacations down to a week for our last 2 trips and the next one coming up in 8 days. While it's pretty doable for most folks I really do miss our long relaxing vacations and hope in the future we are able to go back to making it a 2 week trek. Right now your 10 day trip sounds really good to me!
Also, something to consider...
If you are pretty sure you will be back the following year you really might want to consider purchasing annual passes. If you get in 10 days this year and another 10 the next year it will most likely be a good deal. 20 days on one ticket! Just have to make sure your second trip happens before your AP expires. Anyway, the AP can pay for itself after so many days plus you get the discounts on shopping and food. (and tours) Even if you don't want to go the AP route for your entire group you might think about getting one AP just for the discounts.
Who knows if you end up loving your 10 days in the park....... if you have an AP you might decide you want to stay even longer next time.
