I assume that you're starting from just the Core set then?

I think the best add-on would be the Secrets of Arkham expansion, but this is a bigger expansion than the individual asylum packs - it costs a little less than two asylum packs would but you get a lot of cards in it.

If you don't want to go that high and you just want to pick up one asylum pack, I'd go with anything in the Ancient Relics cycle or the Yuggoth Contract cycle (a cycle is six asylum packs).

Probably if I had to pick just one to recommend, I'd say The Shifting Sands because it also comes with an extra set of story cards (so does Secrets of Arkham actually) which will give you more story effects to see. Just that little bit over what a typical asylum pack includes...

I would second the Secrets of Arkham love, especially for the casual player. Lots of strong cards for all the factions and worth the cost (about twice that of a smaller asylum pack)

I think you can get a really good feeling for the basic game just from the core set. If you like the game, and plan to do any deck building (even if just for you and your wife) I would suggest getting a second core set as well, so that you can have two copies of each of the cards. It will make building basic decks a lot easier.

Have fun and stay sane!

I placed the order last night and added the SoA expansion. I was tempted to add a bunch of the older packs that had been marked to $6...but I figured I should probaly wait till I actually played this game and fought out I like it first

So originally, Call of Cthulhu was a CCG and there was no such thing as an LCG. As sales dropped they had plans to cancel the game, but as a final gesture of goodwill they took the cards they had already made for the next set and decided to release them in fixed-content packs. And, they were an unexpected hit! Thus the LCG concept was born, and the game was redone into a newly invented format.

Actually, it's probably a good thing you resisted those. Let me explain why...

So originally, Call of Cthulhu was a CCG and there was no such thing as an LCG. As sales dropped they had plans to cancel the game, but as a final gesture of goodwill they took the cards they had already made for the next set and decided to release them in fixed-content packs. And, they were an unexpected hit! Thus the LCG concept was born, and the game was redone into a newly invented format.

But, the LCG idea was still rough and influenced by the CCG style thinking. So, the first LCG packs came with 40 cards - 3x copies of ten "common" cards and 1x copies of ten "uncommon" cards. The idea was that players would buy extra packs with high wastage to get 3x copies of the uncommons. And hey, why not? Isn't that what they'd been doing for years in CCGs?

But over time, they realized that the audience was different and people didn't WANT to buy all those wasted cards - players were coming from boardgame backgrounds and not just CCG backgrounds. So, the format was redone into the modern LCG distribution. Packs contain 60 cards rather than 40, with 3x copies of all twenty. Because of the increased size, the packs are now $15 retail instead of $10 retail but you only need to buy one instead of three so for most players it's half the cost while for the most casual of casual players it's only moderately more.

Long story short, all those $6 packs you see are the old 40-card versions still sitting on the shelves. Nearly all of them have been reprinted and rereleased in new 60 card versions now, with only the Dreamlands cycle left to go. Personally, I would consider carefully before getting them because if you decide to get into the deck building aspect you'll want full sets of cards. Also, they have poor resale/trade value because most other people will want full sets as well. However, if you don't care about that they could be a good deal. Also, in a sense you're doing a community service if you pick up the Dreamlands ones because it's been said that Dreamlands will be redone in the modern format only after the existing stock is sold. So if you do decide to get some, start with those