We're going in May as well!! May 9-23!!
I have a question though, we are going for 2 full weeks, 14 days! ...but online, tickets only go up to 10 days. Does that mean it's more economical to buy an AP?
I haven't been to Disney since '97

But when we did go then, our room keys were our park tickets, and we had admission for the entire length of our stay. I didn't see an option to do that this time. (not past 10 days at least).
I haven't done the math lately, but it used to be a break even on the AP when you exceeded eight days of park hopping.
The only folks who can purchase a 14 day pass, at least to my knowledge, are those in the UK or Ireland--
Undercover Tourist offers an "Ultimate" pass for them.
Unfortunately, the "length of stay" pass was discontinued by Disney for our convenience.

Personally, I loved those passes until I purchased my PAP. I dislike with extreme intensity the "options" for purchasing passes now--too much of a

when you buy online to be sure you have got the right ticket, you know what I mean, hopping or no hopping, water parks or no water parks, expiring or nonexpiring--length of stay was much easier. . .but that's just me.
I would simply calculate the cost of a 10 day ticket plus the cost of a four day ticket (the type and size you desire, i.e., hopping or no, water parks or no, expiring or nonexpiring

) as compared to the annual pass you prefer, i.e., Premium Annual Pass which includes water parks and DQ (no longer a good bargain IMHO since there is no more PI) or the regular AP.
At least the simple math here is easier than figuring out if you are purchasing the correct ticket for your needs.

Tongue is firmly in cheek here, it really isn't rocket science, just more a pain than it used to be with the Length of Stay passes and its like predecessors.
Hope some of this is of benefit to you in your decision to purchase passes.