Should you order the most expensive thing on the menu?

Didn't realize just how much alike Blanche and I were until tonight. She and Dad took us out to dinner frequently, inviting Larry and Roberta, Toni and Kim. Richard lived at home then and was not attached. Blanche didn't really entertain Richard's girlfriends, maybe because he didn't want them there. Anyway, we went to nice restaurants and she always picked up the check but she would say that if you ordered lobster, you wouldn't be invited back! None of us ever ordered lobster.
Tonight I invited the Polapinks out for dinner because they are moving. I chose Wood Ranch because Paul likes tri tip. I also invited Dianne and Bob because I knew Bob liked the Polapinks and would like to say goodbye. I told him I would treat since they had had me over several times. Little did I know... no lobster on the menu but Dianne ordered filet mignon and a salad and was the only one except Ava that wanted dessert. I just thought it was interesting. She ate half the salad, half of everything else and then took the rest home. She wanted the dessert to go because they offered it for free. Bob stopped her. In her defense, I don't think she gets out much. I was just really surprised since she was so tacky looking at Lloyd's wedding. Okay I'm not that nice! I guess I have a problem also with when you are someone else's guest and they know you drive an 11 year old car and work for a living, is it good manner to order the most expensive thing on the menu? When my company "takes me out to dinner", I have no budget. I stay in four star hotels and eat in great restaurants but don't feel I need to "take advantage". I guess that's how I felt about Dianne ordering. When I first went to her house I was amazed at the filth, disrepair, dog hair, whole in the floor. The plumbing had broken down and they were urinating in a bucket and pouring it down the shower. I went to take Bob some fried chicken. Can't remember the reason. Couldn't believe he was living like than but he was still drinking heavily. I had heard that he slept in the van at night. Anyway as soon as Bob got a dime, he bought her a new double wide. Suddenly she needed a Wolf range on which to cook. Needed a Vermont ham to serve to a bunch of young people that didn't know the difference between that and Vons spiral cut. Am I missing what is going on? Before you judge me. Know that I have had to do without! While raising Lloyd and Elliot, I had very little extra because I thought it best to hang onto my house. It provided stability and continuity for them. When I finally did have money again, I didn't live large. I realized how little you really need to live and be happy. I have problems but I am happy. Blanche on the other hand guarded her money as her most prized possession. She felt that others did not have the right to be extravagant on her dime. She felt you could be extravagant with your money not someone elses. Interesting...