Is he just taking an oral antihistamine or is he taking other things (nasal steriods and antihistamines) to help? Any eye drops?
There are some really good treatment options out there that include both symptomatic treatment and allergy shots to try to reduce his symptoms over time. I'm sorry your husband has been so sick! If you love Disney, I would seek treatment.
I used to be so miserable as a kid. The allergies made me miserable and the antihistamines put me to sleep in class. I started aggressive allergy treatment with pretty much every type of allergy drug you can think of along with allergy shots when I was about 20. Over time, the allergy shots have really helped - it has made my asthma manageable (I'm actually off daily meds now!). Now I only take oral antihistamines as needed during the fall and spring. Sometimes, if I am having a really bad day, I will take some allergy eye drops. That is worlds away from where I used to be.
While everyone has a different outcome, I am glad I started seeing an allergist and went ahead and started allergy shots. My first allergist did not put everyone on immunotherapy (allergy shots), but my current one seems to throw everyone on shots. I'm not sure that I like that - I think that you should only do it if you can't manage your symptoms with more conservative measures due to the risk. But if you are miserable despite trying all the available meds, it is well worth it.