Cold finished basement
One of the biggest things to the feel of a room is the floor temp--you mentioned that yours feels cold. A thermal padding and carpet will be the biggest bang for the buck in the feel or that is what I have found reducing the heat transfer from the floor that has no insulation to a minimum of carpet and a thermal pad has made my basements warm enough that the kids played on the floor. Prior to that they did not like the basement because it was cold even with a 72 deg air temp.

Heat vents being low sure that can help a little but the ducting probably services the main floor so moving them to the floor ends up costing more because you end up running new ducts from the trunk lines. The other thing I found that helped was IR heaters but they only heat a focused area but they work well for a seating area and a zone the kids usually play on the floor in.