Spicing up a marriage and/or your sex life is a great idea, but there are lots of different ways to accomplish that, AND — get this — you can even continue spicing things up after you have kids, so you really shouldn’t feel pressured to, like, have all the crazy fun now because you won’t be able to later. Life — and love and sex and fun and everything else — still goes on once you have kids. Yes, it’s different. But it doesn’t all just end once you become a parent.
Whether this particular plan you have to spice up your marriage in advisable, I can’t answer that for you. It’s something you and your wife have to think about in relation to who you are as people and as a couple. I do have one piece of advice in determining whether this is a good choice for you: don’t wait until Valentine’s Day. I mean, what’s the point in that anyway? To have something to look forward to? Or to put it off because you’re scared? I say move it to next week and see how that feels. If moving the date so close that it’s real and not just hypothetical makes you feel more sick and anxious than actually excited, then it’s probably not the right choice for you. And that’s fine. If this doesn’t feel right — or if you go through with it and it’s not a good experience — you can still find other things to do as a couple to bring some excitement into your marriage. The key is to be honest about your desires and your boundaries, and to push yourselves a little outside your comfort zone but not so much that it feels more like a test of your will than having fun.
Also, you said your wife asked you to suggest things, but did you ask her for suggestions? One evening the two of you should make a list of all the things you want to do together — sexual and otherwise, fantasy and reality — and when you feel like you need a little spice, re-visit the list and pick out something together to try. And, of course, this should go without saying, but, if you do decide to include someone else in your sex life, be smart, safe, and discrete about it, and reassure your wife that she — and you — can change your mind and back out at any point.
If you have a relationship/dating question I can help answer, you can send me your letters at firstname.lastname@example.org.