I tried racing without a spare in a sprint last year and flatted out 1/2 through the bike course. Let me tell you, that sucked and I'll never do it again. Clomping along on a long hot Florida highway feeling like an idiot until a compassionate chiropractor picked me up. I did the run anyway, but I had to DNF. Stupid. I ride clincher's so I'll leave the tubie advise to others.

I'm just an average joe, but here's what I do:

Bring a spare. For certain. Not even a debate here. All that training down the drain if you flat. Not worth it at all.

As far as tape/glue, I use a lightly used tubular as my spare. Its already stretched and its already got two layers of glue on it. Even though the glue is not fresh, it bonds great with 130 PSI and a couple of miles of riding. Just try and pull it off when you're through :). Once you're able to get a grip around the flat tubular (this is the hardest part--for me at least) changing a tubular only takes like a minute (assuming that you're using a pre-stretched spare) to change a tubular.

As far as where to put it, I use an old toe strap or a piece of velcro (You could even use a cable tie) and strap it to my seat stays/seat post. I keep a tiny saddle bag under my saddle that is big enough for 2 C02s (I had a race this year where I flatted twice but was able to reuse the original tubular, so now I bring 2 CO2s!), a CO2 chuck, 5 piece Crank Bros. tool and a single plastic tire tool. I cinch the spare tire tight enough that it doesn't stick out into the clean air (i.e., you can't see it from the front).