If it was me, given your parameters, I'd say 3 day/2 night. I would select Sun - Tues.
Because you are at GC, you get EE on both Monday & Tuesday.
Since it is April, you would want to go on Sunday so you could ensure seeing the Fireworks & the Aladdin show. (this was exactly our criteria on our last visit.)
2 1/2 - 3 days should give you time to see most everything, especially if you utilize EE effeciently.
Being a WDW Vet you should read (& print) most of Hydroguy's thread "rules" as these will be helpful & will answer alot of questions.
Have fun.
hound