My kids also loved their first day.
My youngest was worried about having a male teacher. I think he is the coolest teacher ever. He studied/lived in China, so he has kites, chinese artwork, and chinese sayings all over his classroom. Dd has a pen pal of sorts who studies chinese and always sends her a postcard with chinese writing, so this was very auspicious for her.
My oldest dd also liked her new teacher; but I didn't get much out of her. She has several new kids in her class, and most of them seem very cool.
I spent the first 1 1/2 hours with youngest dd in her classroom. The teacher put me and another dad to work, and then told us "Stay as long as you want; stay every day! If you want to stay on a regular basis, let me know, and I'll work you into the lessonplans." That is the first time I have ever been specifically invited; sure, most teachers have said to me "Oh, we'd love to have you come and visit any time." but this seemed different, and more sincere.
He did a ton of math manipulatives. They monitor how many days they are in school, and they do it with tally marks, money, one/ten/hundreds units, etc. I think that is totally cool. He also has a student of the day every day. The student is called "The Big Enchilada" and gets to have the trophy (which says "Big Enchilada" on it) at their table. He writes a biography about the kid for the others, and then at calendar time he tells a fantastical story about the child. He sounds like a generally goofy, loving guy. Dd was like "Uhhhh, I think I really like school. I wonder if I can have Mr R every year? I can't wait to be the Big Enchilada!"
I'm so happy they love school! I'm so happy *I* love their school!