I've visited Excaliber, but not stayed there. I think it's a great place, generally, for a large group of multiple ages. Not sure about the rooms/accomodations, though.
We stayed at the Tropicana across the street at a great price and LOVED it! Inexpensive, great pool area, wonderful drinks and a swim up pool bar. I think it was only about $10-20 per night more than Excaliber, and the fun stuff would still be close by. There were lots of kids around.
I have to share my family experience of Monte Carlo though......keep in mind, however, that this was about 10 years ago, so there could be changes....
Their pool area is what made me choose that place, as DS was two and other DS was 6 months. The pool was nice, though my kids were the only kids there the entire week. The water was cooler than I would have expected, especially in the wave pool. The management were flat out rude and we had issues with them putting a $500 hold ($100 per day) when we checked in, but not letting us know and us not giving them permission. (This, by the way, put a huge damper in our day trip to DL. For 7 of us, we ended up only having $100 for the entire day!!! We had counted on that money on our card for spending money while we were there.) Monte Carlo continued to indicate that they didn't do anything wrong.
Also, at the restaurants, they had no kids menu and the buffet had no children's prices. We had to pay full price for DS who was 2, thankfully, not the baby. They also only had two high chairs at each restaurant, making it a big challenge to eat. They had issues with us using the stroller through the casino, even though that was the only way to the front door from the hotel rooms, they gave us negative looks when we had DS in the stroller by the pool and there were almost no changing tables in the bathrooms. Now, I know Vegas isn't all about kids or anything, but those are some of the attributes to a hotel that I would consider "family friendly" or "kid friendly".