I keep thinking that Pluto is sort of like what people say about tenure, which is once you let that first iffy entity into the club, then you have a precedent and later things that come along get compared to whether it meets the same standard as Pluto as opposed to whether it seems planet-worthy in its own right. I certainly know people who have started at new jobs and looked up the most marginal successful tenure case on the books so they could tell themselves, "Okay, so long as I'm as accomplished as this person, either I've got a job for life or decent grounds for a lawsuit."
Since planets can't sue, they could have just kicked Pluto out of the club. One thing that especially annoys me about these new planets is they screw up the mnemonics. Back when I was a boy, you learned "My Very Educated Mother Just Served Us Nine Pizzas," and you were good to go on the order so long as the first-letter hint was equivalent. Kick Pluto out, and you could just change "Nine Pizzas" to "Noodles" or "Nectarines" and all was well in the universe.
Now any suitable mnemonic sentence is longer, and I'm not even sure what you are supposed to do with the Pluto/Charon double planet. Maybe a sentence that has PC as its penultimate word, but try figuring out how to follow that with a word starting with X, if this other planet really does end up being called Xena.*
Boston/Cambridge has a to-scale model of the solar system around the city. Mars is in the mall where Kathryn and I went shopping last weekend. I'd seen Mercury and Venus before at the Science Museum. I don't remember where the 11-foot wide sun is on display, although obviously it has to be nearby. Pluto is at the Riverside T stop, where I've actually been, but didn't know to look for the planet at the time. I could see where this could be a good weekend photoblogging expedition, but I have work to do and still haven't figured out when/how I'm going to see Snakes on a Plane.
* BTW, JFW readers will remember this spring I was assigned to write a 26-sentence story where each word began with a different letter of the alphabet, so I'm recently familiar with the task of accommodating X demands.