For instance, on the past several trips I have brought a bankroll of $500.
$200 I designated for single line play (Loose Deuces quarters with an edge, my favorite).
$200 I designated for multi-line play (usually Ultimate X, a Wheel game, or whatever looks interesting at the time)
$100 I designated as my "pot shot" money.
I tend to increase the volatility as my trip goes on, starting with the single hand which can take quite a while, then escalating to multi-line. I don't often play for hours on end... I'm usually hoping to get a few hours of play total in each trip. This trip I had a machine that just wouldn't let me go... wouldn't give up the big win, but also wouldn't lose. After about 2.5 hours of that nonsense and up around $60, I actually had to change casinos.

The goal with each of these "bankrolls" is the same. Double my money or die trying. For example, if I win $200 on single line, I'll pocket those winnings for the rest of the trip. If it's a nice win early on I will pocket at least the original $200 and the $200 won and decide if I want to play a little more on the remainder - but usually I'll stop right after the big win and move on to the next bankroll.
Multi-line of course goes faster than the single line, but offers some nice opportunities with more lines and usually multipliers. This is probably where I find the most actual enjoyment- while it lasts.
The "pot shot" bets are always incredibly high risk- $5 single line machine, 10 play quarters... whatever I'm in the mood for. Usually to cap off the trip. I will win or lose in about 30 seconds (and believe me, I expect to lose), but it's a nice thrill and a chance to win something I couldn't win in my other play.
This most recent trip, I bombed out. Previous trip, I had the pleasure of winning in all 3 categories (hit loose deuces for $625, multi-line winnings that added up to $250 (triple wheel, spin and ux) and caught a pot-shot $5 "royal with deuces" for another $625 on about the 5th or 6th hand of my final bankroll.
Curious if others split their bankroll in this way. If not, give it a try to spice up your game.