i have been to meribel 4 times
it is in the 3 valles area which is huge ( courcheval, val dsaire and meribel) meribel is the best to stay in as it is in the middle . i would recommended getting a 3 valley pass. there are two parks in meribel: meribel moon park which had quite a few large jumps but not many rails and then the motteret park further up the mountain. this had a superpipe several kickers ( small 3 line and 3 larger jumps ) also quite a few rails ( flat/rainbox box flat rail and several other creative features. also a boardercross and some lumps.
val dsiere also had a good park with a large kicker line and a large step up to flat and then a drop off.
also a hip with a barrel several smaller jumps and a variety of rails.
courcheval didnt really have much in the way of park