Easiest Coin Series To Collect?

I know this is really about USA coins, but my easiest collection to complete was the "Canadian" Prince Edward Island penny/cent set. I was able to complete two whole sets in a couple days.

Roosevelt dimes, even with the silver ones, seem to be pretty widely recommended to get into for an easy collection.
Any thoughts?
I had considered standard Washington quarters. However, it seems a lot of the earlier silver ones are not too cheap and basically not really easily obtained through circulation/coin roll hunting. Oh, that and the fact that I can't seem to find a Dansco album for standard Washington quarters 1932-1998 ANYWHERE.

Would Roosevelt dimes be recommended over Washington quarters?

jbuck, I actually agree with you. Going over things recently, I noticed how expansive and costly the Washington quarter set is. I mean, that's like 30 years worth of silver coins that are pretty hard to find in circulation. I mean, besides the 1932 dated ones, they aren't really that much. I've seen them go for 8-15 dollars or so. But yeah... For me personally, 8-15 dollars for each coin, for 30 years of coins is a lot of money!

I've kind of been looking into returning to some of what I'd call "roots" of coin collecting and trying to find some series to collect that don't require a ridiculous amount of time going to shows/coin stores to obtain them. I started with searching through nickel rolls to fill out my Jefferson albums, and it was extremely cheap and pleasing. I did purchase some coins as well, though, but found many in circulation, even the older ones.

A few more cheap series to get into it seem would be:
Lincoln Memorial cents
Shield cents
State Quarters
Kennedy half dollars

My Buffalo nickel album is also coming along slowly but surely.
I started out mostly acid dated treated coins in 2x2's. I now am looking for much better examples for my Dansco album.

My Kennedy half dollar set is also fairly inexpensive. I am missing a few of the 1964 silver coins, though. The rest are all clad coins, so it's just a matter of finding them honestly. Sometimes my credit union will have a few loose ones. They never have rolls, though.
I would be interested in adding some of the earlier silver proofs and SMS coins, but not sure how to put them into the mix. I suppose a blank page would work at the end of the album.

I really like Susan B Anthony dollars, and they are by no means a hard set to complete. Obviously, the most expensive coins are the two type 2 proofs from 79 and 81. I currently have the 1981 type 2 proof, but no other proofs so far.