As you inquire, you will likely get comments from some who prefer to travel at a slower pace (which is great for them) but your plan sounds good to me. We did a trip of similar scope in November which I wrote about here http://www.flyertalk.com/forum/trip-...tr-w-pics.html and had a great time. If you want to put your companion pass to work and use the minimum amount of Avios, you can call BA and ask for availability BOS-DUB-London on Aer Lingus and use WN for DAL-BOS. However there are DF-ORD-LHR or DFW-RDU-LHR options on several days in early May which would be far easier and more efficient at only 20K miles per person.

Try looking at using AA miles to LHR on 5/4, 5/7 or 5/12 and UA miles for the return.
Edit: The LH FRA-DFW flight has 3 award seats nearly every day in May, and there are many UA and AC options as well returning from ZRH or MXP with taxes of $50-$90 per person. FCO has less available dates but is also possible.