It feels like most people have a sense of dread or despair for milestone birthdays like these. I don't feel that way. But I wouldn't say I'm excited either. Full disclosure I get really excited about finding a grey hair, "I'm Mom-the-Wise now!"
Birthday's are a day that I get to have all the say in activities and food choices, that's really enough for me. Mom's generally don't get that. We are often the ones who bend our wants to make the kids or spouse happy. But we are guaranteed two days a year where we can say, "everybody back off, we are eating pizza with pineapples and anything with dark chocolate!". Nom. Nom. Nom.