Highly customizable flight search engine?
 

I'm looking for a flight search engine for a multi-city itinerary that will allow me to customize alternate airports.

This is kind of complicated to explain, so hopefully I can make myself clear. Basically, I'd like to take a trip from NYC to ITH to TUL to NYC, but am willing to consider SYR as an alternate airport for ITH (even though they're not typically considered a pair) and OKC as an alternate airport for TUL, in order to save some money and hit my stops at the times I need to be there. This all gets further complicated by the fact that my last flight (TUL to NYC or OKC to NYC) can be on either one of two consecutive days, but the first two legs must be on certain days.

Is there any flight search engine that allows price comparisons with this level of customization? I realize I may be asking for the moon here :)

I know that you can do the search using ITA (link) but you just can't book the ticket there. Just separate the alternate cities you're considering by a semicolon when you do the multi city search:

ex:
flight 1: origin: NYC
destination: ITH;SYR

Try Kayak, multi-city, include alternate airports. Not sure if it will do what you need, but I've used it for flexible planning with alternate connection cities, layover durations, total flight times, etc.

CPRich, Kayak was what I was using before without too much luck. However, ITA worked perfectly for what I wanted - thanks, aerospace!!