Overall good itinerary and choices! I would change/recommend the following:
-The Radisson Decapolis is nice, but if you really want to give a "nicer experience for the lady" I would go for the Belmond Miraflores. You will note the price difference but I thought it was worth every penny.
-Sunday through Wednesday is perfect. Tambo del Inka is great, as is a full day to explore Cusco and nearby. In Cusco, I would recommend the Marriott (have not stayed at the Best Western). Not sure about 2 days--it all depends on your research and how much you want to cover, as opposed to 2 days in Lima. It could also depend on whether you think you may return to Lima at some point (easier to do), than to Cusco.
-I would suggest returning CUS-LIM on Thursday night to have an entire day in LIM. Personally, I would avoid airport in the morning and airport at night as driving out of LIM and into the city, and getting back in for your international dep. can be very time consuming (traffic).
-Lastly, this could be of some help: http://www.frugaltravelguy.com/2014/...hu-picchu.html.

There is plenty of time from here on to April and hope we are able to answer other questions you may have. Still, research as much as you can!