It may be seem too obvious/cliche but Paris is the best answer for this.
There is no beach, but if you want to play in the sand you can go play petanque down by the canal.
Best street skating in Europe. Just cruising around the city is fun. It's a gorgeous city. The nightlife is great. Depending on the week you may intersect with Mens fashion week, so it may be a pro or con depending on what you can tolerate.
Berlin could be fun too. Again, no beach, but you can sit by the river. If you go in June you'll probably have decent weather. And try to get into some clubs at night.
I live in Northern Italy. I wouldn't recommend it if your primary goal is skating. If you want to have a nice holiday that's a different story, it's a great place to chill, have an aperitivo, go up to the mountains, etc., but for skating, it's not the best.