My 4 year old daughter is the same way, quite often. If I try to sit down on the steps to chat with parents, she is all over me, climbing in my lap, tugging on my hand, etc. I do my best to stay patient, speak calmly and firmly to her and remind her that I can speak with her in a few minutes. I agree that a little extra time after the kids are gone, to read a story or play a game or whatever will help. Even though I have dinner to make, toys to clean and dishes to put in the dishwasher, I know it's tough for her to share me all day with other kids. She is just trying to claim her Mommy back again.
I have also said to the parents "Sorry, this time of day is tough for her. She is pretty overwhelmed at this point!" All of them have expressed understanding. So I do let her climb into my lap, etc. As long as she is not MISbehaving, then I don't mind some snuggling. After all, when moms and dads arrive, it's thier job to put on shoes and coats and so on....so why not?