If your wife has trouble taking pills regularly, which is one suggestion, then I would suggest and IUD. (Intra Uterin Device.) This is a little T shapped thing they put inside the woman and it lasts for 5 years, but can be removed sooner. One brand name is Mirena, which is hormonal, but they also make ones of copper. (You shouldn't use those if you're allergic to copper.) IUD is a great choice if you are planning to become parents in the future. Fertility returns once it is removed. You don't need surgery to do this, it is a simple insertion done by your doctor right at their office.
The risks with IUD are ectopic pregnancy and pelvic inflammatory disease. The first one is random and actually is a risk with all women anyway, but if your wife has already had one of those before make sure her doctor knows. The second risk is lessened greatly by staying monogamous.
It is good your wife stopped depo. I was on depo for two years. It kills your libido and greatly reduces your bone density the longer you take it. It can take more than 18 months to fully recover once coming off of it.
I hope this is helpful for you and your wife!
If your wife is sensitive to hormones, I wouldn't recommend using the Mirena IUD. There is a caution in the literature about using it if you are prone to depression. I wasn't diagnosed yet, but I tried it and got it removed 6 months later. I was so depressed while I had it in. If I had known ahead of time, I would have chosen the copper kind.
Another option is the diaphragm. I was considering that before I got my tubes tied. It may not be AS reliable as the pill or an IUD, but it's hormone free.
I would personally recommend the implant. It lasts for three years and has no major side-affects. It is low/no maintance which means she won't have to remember to take the Pill every day.
Thanks guys. We'll look into the copper IUD