TBH, I don't know if it's such a great idea. Sure we all want and expect to be mourned and missed when we are gone, and we want a little bit to feel like we last a bit longer if we are remembered. But if the main goal is to do something nice for your wife, the question should be what would make her most happy and how will she want to continue with her life. And to give her a feeling that - once you're gone! - your love was so much greater and she'll never find another one like you... well, I don't know. It could evoke feelings of guilt preventing her from "moving on", it could set a higher benchmark for future relationships, and so forth.
I think it's better to focus that energy on the now and build good memories together. If you already are, all the better. But respect that once you're dead, you're dead and I don't think you have the right to reach beyond your grave and influence her on her future course.
People deal with loss in very different and very individual ways, I am not arguing that in some cases it may help positively, but I am also sure that in others it could have negative effects. Human memories are the way they are for a reason, and the ability to "forget" or to recreate memories in slightly different ways when remembering them is an important aspect in finding happiness.
I am sorry if it sounds too harsh, but given that we are dealing with hypotheticals anyway I felt it was OK to voice this opinion here. And before anyone asks - yes I am in a happy relationships for almost 20 years now, and we've been through some very dark times as well, but there is no uncertainty whether we'll be together till one of us dies. But then again, both of us are very much centered in the now and not big on memorabilia and traditions (mixed race and mixed religion relationships are often that way I guess), other than a little box of pictures condensing memories of almost 40 years. We are both big believers that the more energy you spent for the past or the future, the less you experience the now. Keep what you must to help you through the now and what may need in the future, but no more.