I heard the opposite for X2, that its nicer in the morning, and when I was there for west coast bash a few months ago I found that to be true, it did feel a little less rough in the morning. Its not really your head that gets hurt on that anyway, its your legs (specifically your calves as they slam into the seat on the last raven turn). Riding in the inside on the back row also helps.
For Viper, ride in the first row of the last car in the train, it's the "magic seat" and smoother than all the rest.
My recommendation nowadays for first ride of the day is Superman. Since they almost never run both sides, the line is among the slowest in the park, and Flash Pass is limited to Platinum, going there first works great for me. Most people don't go to that area in the morning, so if you head right to Orient (Helpful Honda) Express when the park opens, you should get at least 1-3 walkon rides on Superman.
Is Superman relatively close to X2, or is hard to line those up back to back for early rides.
Apology for the double post.