I think the award ticket idea is a very good one. When I studied in England for a semester one problem that I ran into is that a lot of the cheapest fares have stay limits (like 30 days or so). As such, I ended up being on the hook for a much more expensive fare. Another option is to look for charter companies, (I actually ended up flying out of Toronto on Air Canada who did not have as onerous stay limits, but I nearly bought a ticket on Air Transat).

With DL miles and some flexiblity you should be able to pull off a decent award. I know that DL has started several new services to Europe, some of which are not doing all that well. I would look at their route map and be a little creative. (For instance, I know that SNN has availability for pretty much the entire summer ex-ATL, although the connection to Paris may be difficult).