Played 3 IRL Prince games tonight with my wife, using the blank cards as proxies. Also mostly Guilds games, as that was new to us as well. For the first 2, we used mostly recommended Kingdoms with Guilds and Dominion, but replaced something with Prince. Third was picked out with stuff that sounded fun.
Game 1: I wasn't allowed to buy Prince, and she had to buy Prince, so we could see the effects of ignoring Prince. She promoted her Advisor to a Prince. The 7 card starting hands were nice for her, but she had no use for the extra action except on 1 turn. She did put together a fun little combo where she would Stonemason her Estates into 2 Coppers, and use Moneylenders to trash the Coppers. I won with some sort of Laboratory/Festival/Merchant's Guild engine. Ended the game by 3-piling with the help of Stonemason. My wife had also bought a Stonemason for $10 to get 2 Princes, which she planned to Stonemason into other things, but didn't get the chance.
One thing I noticed is that while Stonemason for $7 to get 2 good $5s is generally great, if you do it too much you end up with a bunch of Stonemasons that are just in your way.
Game 2: I had to buy Prince, she wasn't allowed to. I used Prince on Candlestick Maker. The free coin token every turn was pretty nice, but that's about it. I bought a second one with the plan to use it on Militia, but didn't collide. Mostly it was a Soothsayer game. Ended with my 5 Provinces to her 3.
Game 3: The Prince powerhouse. Herald, Navigator, Outpost, Prince. Loan to trash the Coppers. Also Colony game. Need I say more? I had both a Princed Herald and a Princed Navigator... that was just ridiculous. It meant Herald would always succeed. I also at one point bought a Herald for $6 so that I could put Herald and Prince on my deck. Before too long I was getting over $20 per turn easily, including Outpost turns! Twice I had to spend well over $10 on a Market so that I could have +buy. Though she got an earlier lead on the Colonies. I won 5 Colonies to her 3.