Clubworld had high roller slot bonus, deposit $150 get $500 bonus. I took this offer and spin at usually $2-$2.50 per spin because the playthrough was very high. I felt like the slots were not the same as when I spin at my normal bet size ($1 to $1.25), it took me a long period of time to get to the bonus rounds or free spins, sometimes I didn't even get to the bonus rounds.
Eventually I lost it all quick even with the large balance to start with, but I had a chance to play progressive slot with real money. I played Jackpot Pinatas and I really like its bonus round where you pick the pinatas 3 times for your bonus and it will give you number of free spins according to your pinatas selection. I had screen shot to show, it was not a big win, but I just took the screen shot while I could because I knew I wouldn't spin at $5 per spin for long, hehe.