It's easy enough to understand the text on the card; if they didn't figure it out, you can give them that "ah-ha" moment by playing it and revealing a hand with one more Menagerie.
No, that's not what I meant. What I was hinting at was that the beginner will have trouble getting his deck into a state where he can consistently activate it. Menagerie is a pretty high-skill card and its primary redeeming quality in this kingdom is that it's fun to use... when it works (it also strengthens the engine). I suppose that if you didn't have the base set and wanted to design a first game kingdom, Menagerie would work.
Plus, it exacerbates Village-idiot problems because Menagerie is a cantrip when it fails.
Moat's presence is quite important for a first game I think. Notably, a lot of people's first game will be with 3 or 4, and there, Moat is definitely a card worth considering - throwing 3 militia BM and 1 moat BM into the simulator, Moat wins 60%, while the three militias win about 11% each. Of course, this doesn't tell you if it's actually good in a real (beginner) game, but I suspect it often would be.
But the OP said that he was going to introduce his wife to the game. That heavily implies 2-player, at least to me. Furthermore, in actual gameplay, you're not going to have 4 players going for some sort of BM.
Anyway, I think Matt_Arnold's suggestion is great. I personally don't own the base set and contemplate from time to time how I would introduce beginners to the game. Some suggestions that I have for good cards to include:
Courtyard - Short, sweet, and simple. It's also $2.
Masquerade - Also short, and passing cards is interesting and not very confusing at all. It's a trasher, and cheap at $3.
Conspirator - I'm kind of loath to include this card. Its redeeming quality is that beginners would love to activate it.
Trading Post - Pretty basic trasher; I suppose it's also good at demonstrating the strength of Silver, but in any case, this helps all sorts of strategies.
Lighthouse - Moat that's not in the base set; problem is that it's a Duration and it's spammable.
Fishing Village - I'm just a little bit concerned about the strength of this card, and also the fact that it's a Duration.
Smugglers - Might be fun for a first game.
Warehouse - Very basic, and it's like Cellar.
Caravan - Again, concerned that it's a Duration and very easily spammable.
Cutpurse - Probably not good with more than 3 players.
Salvager - It could be a little difficult to get beginners to use this card.
Bazaar - Only vanilla bonuses.
Wharf - It's just
so good, maybe too good.
Apprentice - Same deal as Salvager.
Possession - Nah, just kidding.
Obviously, Potion cards are no good in first games. Otherwise, I'd totally love to play with Apothecary.
Worker's Village - It's Village with +buy...
Vault - Problem here is that it's a little too wordy; otherwise it's not a very difficult card to understand.
Fortune Teller - Innocuous enough to be on this list.
Menagerie - Already been discussed to death.
Farming Village - This is really wordy for the end effect, otherwise it's probably okay.
Jester - It's a fun card when you hit something good.
Oasis - The issue is that it could lead to Village-idiot problems.
Oracle - A cheap, somewhat innocuous attack.
Cartographer - I feel that the strength of this card will be lost on many players.
Embassy - The +5 cards just makes this look awesome; it's also a simple card.
Stables - Given that the likelihood of trashing Coppers is low, Stables at least gives players something good to do with them.
Armory - It's like Workshop! Could lead to some rule confusion. Or it could lead to Armory, gaining Armory, then Armory, gaining Armory...
Ironmonger - Issue is that it's wordy.
Scavenger - It seems pretty basic; the second part could lead to some rule confusion, though.
Catacombs - It's pretty much perfect for a terminal +3 cards, but it's too bad that the on-trash clause clutters it a little.
Hunting Grounds - Same deal as Catacombs, except +4 cards.
I'm sure plenty of good kingdoms can be made from these... and this list is by no means exhaustive.
If you don't mind introducing Durations to new players concurrently with everything else, Seaside looks like it has the best options. I deliberately didn't include alt VP or kingdom Treasures because, let's not confuse people here. I suppose that Harem and Island wouldn't be terrible ideas because they do something in your deck, but when I played my first game, I couldn't imagine Victory or Treasure cards other than the basic six.