If this is for a long-term situation because your family isn't going to move from this house for a while, then that could work well. A master suite on the main these days is a plus for many buyers. What you are losing is the formal living room and dining room. Negative here is losing a dining room. I find 50% of my buyers don't care so long as there is an open floor plan with an eat-in kitchen. The other 50% of buyers who have dining room furniture, large families to entertain etc. still want the dining room.
If you have a good sized den and a good sized kitchen, this plan of yours may not really effect the market value of your home, but I have always suggested to clients before doing such a major change to the floor plan of their home, consult with a couple of local Realtors and see what they would suggest. It really depends often where your house is and what is the age group of buyers looking in your neighborhood - what do other houses have in the neighborhood.