I don't have experience with the Aspergers part of it, but I did take a 2.5 yr old on an 8 hr plane ride! And back again! And survived!
DVD player is a great idea and bring extra batterys and more videos than you think you will ever need. Bring all new books and activites... nothing that he has seen before, new will be more exicting. Space out what you give him so that he does not go through it all too fast. My rule of thumb is at least one item for every 15 min of flight- seems like a lot but think about the short attention span we are dealing with here.
If you have not already bought your tickets, consider Jet Blue- they have a personal entertainment system in the back of each seat and you can actually watch it during take off and landing (you can't watch a DVD player then). We always fly Jet Blue to Orlando now and it makes for a much more pleasant flight.
As for the take off- consider noise reducing headphones maybe or earplgs (if they won't bother him). it is going to be very loud.
I hav found that those magazines called 'Playroom' that you can find at the supermarket really occupy my dd for a LONG time. I always pick up multiple copies of those (they have one called 'playroom' and then one wih disney characters, one with Thomas the Tank engine, one with Barney, one with My Little Pony). They are lightweight and I can not say enough good things about them.
Don't bring any beloved figures, because remember that figures will probably be dropped beneath the seats within 45 seconds. I made that mistake and probably spent 2 hrs of the flight digging in the nasty area of the seat to recover JoJo and Goliath.
Similarly, if you bring activity books bring lots of markers or crayons because 75% of them will be dropped during use. Actually, I prefer sticker books, like 'The Ultimate _______ Sticker Book's that you can buy at book stores. They are another item that occupies dd for a long time, are light-weight and don't need markers that will be dropped. If you don't get sticker books (they can be expensive), just any stickers and plain paper can hold attention for quite a while. Michael's (craft store) has good sales on stickers quite often.
I minimize traditional books, because they tend to be heavier and then you will have to read them to him again and again and again. I try to focus on things that dd might be able to do on her own for a little bit, so I can get a little break.
Hope this helps! Just one add'l note: they no longer allow Play Doh on the plane due to the new restrictions on carryons... looks too much like explosives I guess. If you bring it to the airport they will make you throw it away (been there!).