I think it's good to give them as much time on the floor as possible with toys around them, above them, next to mirrors, windows etc. and the more time she has there will give her the chance to learn how to roll as well and sit up etc. If she is crying all the time and not wanting to lay there I would change her scenery around and if that all doesn't seem to work, then possibly get one of those activity centres or you could get some toys to stick on her high chair table for times that she is a bit grizzly about being on the floor. Soon enough she will be crawling around, and then walking so it may not be a good investment $$ wise!