O haven't tried a parallel build yet. I have done a simple twisted pair and that seemed ok.
I've tried both, and I prefer twisted wire over parallel builds. All the little nooks and crannies in the twisted wire help it wick
juice more efficiently, and it's also easier to build (getting multiple parallel strands to line up takes practice). Try a 1/16" diameter coil and it should still give you a decent number of wraps. You can also twist three or even four strands of wire together without much difficulty, which may help you get down to your desired resistance.
Pick up some wire from Lightning Vapes (use code LV15 for a 15% discount for ECF members). Some 24 and 26 gauge wire will work better for you than the 28 gauge. 100 feet of 24 gauge wire costs $7.65, and 100 feet of 26 gauge wire costs $5.95 with the discount, and shipping is free.