How to keep someone entertained when they visit you?

A little back-story here. I found my siblings from my biological father about a year ago via facebook and we met for the first time at my wedding in Las Vegas last September. They live in Colorado and I am from Boston. My 20 year old sister wanted to come and visit for a week on her way to Europe, which at the time we planned it wasn't a problem. Skip forward a few months, I get pregnant with twins. At this point I am just about 5 1/2 months during a heat wave. I can't really walk for long periods of time as I get very tired and dehydrated. I am also not able to take time off of work as I need to use my time for constant Dr.'s appointments and ultrasounds and realistically can't go unpaid as we need every dollar me and my husband make. I explained this to her before she came and she seemed ok with it. But she has been here since last Wednesday and makes me feel like I have to keep her entertained all the time. I did take time off of work last Thursday and we obviously hung out over the weekend. When I ask her what she wants to do I get "whatever you want" but then she acts bored and cranky? I had her come to work with me today so she could see some of the sights of Boston while I am at work (I work in Faneuil Hall which is a tourist heaven) but again she seems bored and is constantly asking "what are we going to do later, tonight, after this"???

My question is more for future reference, how do you keep someone entertained 24/7 when they come to visit you? I try to be a good hostess but I feel like I am coming up short?

Sorry for the rant but this is really bothering me, so any neutral advice would be greatly appreciated.