I like the "messy party" theme someone mentioned...will have to store that one away for down the line.
Our parties frequently have a theme, but only because I find it makes my planning more focused and easier...and pushes me toward greater creativity. My kids choose the theme by age two. I try not to influence them.
It is never character themes. (Though, do you know the "Miss Spider" books? Even before they become some craze, my mom has adored them, so when ds arrived, she sent a couple along to us. My ds now loves them, and we almost had a "Miss Spider" theme for his birthday this last year.)
dfd's first birthday party was at home...a 1980s themed party because she was big into 1980s music. We told her guests to come dressed for the 80s (which apparently was in anyway) if they wanted, and we dressed dfd up like she was our child of the 80s. But other than that and all the 80s music we played, that was about it.
Her second birthday party was also at home, and was a "book party." We did this mostly because that is what dfd said she wanted. She's my little book worm. The side benefit was that we'd just moved to the land of my in-laws, so we were trying to encourage books if people wanted to bring gifts because we don't share values regarding play things for little girls...the theme provided the perfect opportunity. I made photo colorcopies of the covers of some of dfd's books, and we put these on the wall as decorations. She also had a cake decorated like a book. I know there was more we did for the theme, but can't remember.
As you can see, we typically don't go crazy with themes. Just a little something to tie things together in a creative manner.
Let's see. I don't recall having a theme for ds' first birthday. It was at home, and everyone had a good time just hanging out. Second birthday we had at the fire station (that station did free birthday parties, which was great because I REALLY didn't want to have to clean the house for guests to come over only to mess it all up again, and it was an instant theme...plus a theme ds LOVES!). We got a little crazier with that theme because it was just so easy. We had all red and yellow and orange foods, and red and yellow balloons. We put up red and yellow and black crepe paper. We brought in all our toy fire trucks and ambulances from home, including a pop up tent one. We gave as favors firetruck straw cups, which the kids used at the party along with firetruck and firefighter stickers. The kids got to tour the fire station and climb and play in the firetruck, and even try on firefighter gear. And the firefighters gave them each a firefighter hat to take home. There was more, but I forget now.
His last birthday party he said he wanted a surprise party LOL! So cute. The impetus for that is the Miss Spider ABC book (there is a surprise party in it), so we started planning a sweet little Miss Spider surprise party for him. Then suddenly he changed his mind. He wanted a "truck party." As we planned, we had to make it a "things that go" party for flexibility. We had it at our church so I didn't have to clean house. I brought in all our toy cars, planes, trains, busses, etc....both ride-on toys and push toys (we had a nice big room). The cake had trucks on top as decor. We put up "road signs" around the room. Can't recall what else, if anything.
We have also had a roller rink party for our kids, which was a lot of fun and was a built in theme...we all just had to show up and put on skates LOL!
When I was a kid, my mother always had our parties at our house, and they were these sweet themes she created. For example, one year she threw me a baking party. A lot of kids had parties at different party venues, so I did feel a little different (probably enhanced by differences in class), but in retrospect, I love that our parties were always individualized, well-thought out, and made-by-hand by my creative and thoughtful mother. Plus, they were fun parties.
I hope I can give my kids memories like that.
Regarding bedrooms, I find themes to be a little limiting over time. Also, because we are a foster family, our rooms require some flexibility. We don't mind doing quick paint jobs, carefully chosen bedspreads, etc., but we don't do wallpaper, and we don't make any investments in a particular "theme" bigger than a new set of sheets and bedspread (generally just one specially themed one per child). I like a sort of eclectic mix of complimentary and creative decor. My main requirement for kids rooms is that they are designed for kids: nothing on adult level, etc....everything kid sized. My second requirement is that my kids are involved in designing their rooms. I had a kid who wanted an all-purple room. As in, not other colors. And not just any purple. He choose some very um, specific shades, most of them very similar. This was the only room we've ever had that has really been themed. We painted the room purple and found a wooden desk at a thrift shop that we sanded down and painted a glittery purple. We got him a purple bedspread, a set of purple sheets, and some purple pillowcases. Later he saved his allowance money and got some more purple decorative pillows, a purple chair, and eventually, he changed out the curtains so they were purple too. I gave him a purple clock at some point as well. That room was so purple I couldn't stand it, but he loved it, and so that was great. But like I said, that's the only time I've ever done a real "theme room."
I don't see why they are necessary, except for the corporations that want to sell stuff.
I'm pro-adoption reform, but not anti-adoption.