Help with Birthday Ideas

My oldest daughter will be turning 4 on March 27th and my other daughter will be turning 1 on March 16th and I need birthday ideas.

My oldest loves anything princess and disney so suffice to say she has almost all of it. I have no clue what to get her. She did say she wanted the ice cream playdough maker, do your kids like to play with this type of toy or is it a waste, I was also looking at the kid knex or duplo blocks I am kinda disapointed that they aren't more girl options do any of your children play with those. Any other options she loves barbie but how many of those can you actually have without having too many. She got an american girl doll from my parents for christmas, anything to go with that that is a big hit.

Also my 1 year old I have no clue what to get for the second child, she has all my other daughter's younger toys and plays with them but loves to play with my older daughters stuff, what is a mom to do. I found a few things but all my ideas my mom seems to take from me and has already gotten her, any help would be appreciated.

My son's birthday is next week (turning 5) and I was running out of ideas too. He is so spoiled......he really doesn't need anything. So, I went more practical. He will be excited about it. I bought a children's table and chairs and a shelf to go with it. He will have his own "work space" in our office where he can do all his favorite activities like drawing and play doh.
Target had some really cute things inexpensively. I got his table at a local education supply store because they were on clearance.

Or maybe you can get them an outdoor toy or playhouse? I don't know. Sorry, I wasn't more help! It is so hard to come up with these things when they aren't just begging for a certain toy.

As a build-a-holic turned engineer, if she likes to build, she won't care WHAT the lego's/duplo/whatever blocks are. You can still build a castle, it'll just be bright red/blue/green, know what I mean? I actually wrote to the Lego company to complain that the only "girly" stuff was pink and purple (and then they sent me a coupon for said pink and purple lego's, which I refused to use on principle).

Just wanted to throw that out there. I have no suggestions otherwise, lol.

What about some Princess craft kits? My daughter loves them because its one on one time with me (she's 5 and not really old enough to do most of them alone). Then she has something to display in her room for awhile. I like them because once they are done its not something I'm having to pick up week after week!

Do you think I should get a four year old duplo blocks or just regular legos, has anyone bought the kid knex before should I go for those instead?