Okay, this is a mostly self-aggrandizing post to share an endeavor of several months which has recently come to completion:*
After my mom tasted a birthday cake made last fall for our older son, she became enthused at the prospect of my wife and I making my sister's wedding cake. We begged off the project for some time, but eventually were persuaded.
I was the primary baker, my wife the primary decorator; neither of us had a great deal of experience in our chosen field.
All told, though, it was a very enjoyable and rewarding process. The cake recipe I had narrowed down to two, the yellow cake from the King Arthur book and a white cake from Rose Levy Beranbaum's Cake Bible. I practiced a bit with both, and oddly, the yellow (which we chose) got worse over time and the white got better. Both were still good at the end, though it took more practice to get Rose's cakes to an acceptable level.
For the frosting (and numerous other miscellaneous questions) I owe a heavy debt to MAG, who has a terrific buttercream recipe and a great deal of valuable and reassuring expertise.
We were given pretty free reign as far as flavors, decorations, etc., but with one (what seemed to me) major obstacle: no citrus. My read on this was that my sister didn't want the cloying flavor that can be found in bad lemon bars. My wife (quite reasonably) demanded that we take it quite literally. No raspberry-lemon. No Grand Marnier syrup.
We wanted something fun, something interesting, and something delicious. Our (read: my wife's) breakthrough idea: a Kir Royale-inspired cake. We ended up loosely on this theme, and I'd still love to find a way to make it work. We tested champagne buttercream and a champagne syrup for the cakes, but ultimately, it didn't improve the flavor. For a filling, we spread a layer of pureed black currant jam and creme de cassis-flavored buttercream. The outer frosting was a simple vanilla buttercream.
Ultimately, the cake was a hit. It's a bit like the thread about making dinner...for me, the cake was a let-down. Pretty good, but you spend so much time it's hard to be pleased.
Some other notes, though...
It was a great project for my wife and me. Enough of a collaboration to feel like you're doing something together, but enough separate tasks that we weren't stepping on each other's toes.
If you're thinking of doing it on your own to save money....good luck. Between equipment, supplies, and the sheer number of cakes and buttercreams we made during the practice phase...not even counting time...I won't put a number on it, but it's not "worth it" in that sense. For us, it was both wedding gift and sort of like taking a class...and it that sense, it was a good deal.
You could save some money by not doing a bunch of practice runs, and you wouldn't be as bad off as you'd think. I found that, for the initial practice run, I was very careful, we paid so much attention to what we were doing. So much so, that we probably could have used our practice run. It can make you slightly more careless later.
It's sure helpful to have someone who's done this before to lean on for advice (thanks again, MAG!) when your insecurities pop up.
I strongly recommend against taking on this task while pregnant. It nearly wiped Kate out.
It's certainly worthwhile to have a laid back and easy-to-impress bride and groom who will appreciate your work and not get too stressed out.
*Picture doesn't show the colors great, and unfortunately highlights some creases that were less visible in real life. None of the inside shots turned out too well. Han Solo and Princess Leia were placed atop the cake shortly before serving, at the bride's request and to the groom's everlasting delight.