We did go through an attorney because our wills are quite complicated... family, property and inheritance for dd in 3 different countries. All told, even with complications, the bill for us was only $750, however, my cousin is an attorney and she referred us to this guy (she does not do wills and also she is dd's designated guardian and trustee) so he knocked off $250 as a courtesy.
I had asked him about some things I wanted to be designated in the will and he said that they really didn't belong. He said that we could write up these wishes ourselves, but that even notarized they are not guaranteed legally through the court systems. For example, I have a rather expensive set of bone china and silver that my oldest sister has drooled over for years. I already gave her a set of collectible bone china tea pots that she promptly sold on ebay, probably for drug money, although I've never actually confirmed drug use (just suspect it). I specifically do not want her to have my china. Not something to put in the will, but no way to make those wishes legally binding, either. One thing I was able to make legally binding was that she was never to get custody of dd. That, I was able to put in the will.
We had our wills in place already, but I did download (for free) Suze Orman's Will Kit to see if there was anything I could learn from it. I found it to be very thorough and beneficial, especially for someone who is just starting to set up a will. I'd encourage you to start there. I know I downloaded it for free, so check around for promo codes if it's asking for $$ for the download.
I agree, though, that having an attorney is a good plan. They are flesh and blood you can confer with about how to set up your will. Most wills are boilerplate and will just be fill-in-the-blank for you if your main concern is designating a guardian, but there is always the chance that you have something that needs to be discussed. I doubt, though, that in your case it would get very expensive.
Also, I agree with getting a living will set up, especially if you want your dp calling the shots if you are incapacitated. You also probably want a durable power of attorney, which is different than a living will. A will and revocable trust, durable power of attorney, and a living will are the three documents we had the attorney draw up for us.
Good luck! Everyone should at least do the minimum and get a guardian designated for their kids. If there is a power struggle, the kids could spend years in foster care while it all gets hashed out. It's a hard thing to think about, but death *is* certain, so it's a practical affair to take care of. Good for you to be thinking of it!