We spent 3 weeks in the US in March/April last year.

We went to:
LA - Hollywood - Yuck! Dirty, and full of junkies. From there we took a bus to the Grove in Beverly Hills which was a nice day trips.
LA - Anaheim - A beautiful area, and Disneyland was obviously amazing.
Be aware that California is the only state that will not let you travel with kids in a taxi without a car seat, so you'll never to organise transfers with a carseat.
NYC - We LOVED NY, we could have stayed there an extra week, there is so much to do.
Chicago - Was very cold, but we liked it and went to see the Chicago bulls.
Las Vegas - We only went for 2 days and even then we ran out of kid friendly things to do. We stayed at the Vdara, which is a hotel without a casino underneath so we didn't have to walk through a smokey casino to get to our room. Tbh, I won't be going back there again, nothing about it impressed me.
Hawaii - We're not even beach people and yet we loved Hawaii. I agree with the others that you should cut back on others things before cutting Hawaii. There so much to do, and it's great to end the holiday with a bit of relaxation.

I've heard great things about San Francisco, so next time we'll probably drop Chicago and LV for San Fran.

We spent $25k for 2 adults and 1 child so I think $30-35k should be enough for 4-5 of you.