Whenever I trade long straddles, its almost always only with QQQ or SPY. And when I trade them, I always have to use more than 1 contract each, or else commission will eat too much into my profit.
For example. On Tuesday morning I did a long straddle with the SPY. I bought SPY March 135 calls @2.61 and bought SPY March 135 puts @2.86. Total investment: $547 per contract not including commish.
At this very minute, my total straddle is worth $598. Thats $51 profit and if you're not using IB assuming you're retail, you're looking at $20 min for comissh. Thats 40% of profits !
Therefore, when I place straddles, I always use at least 4 contracts.
If you are trading real money, 1 contract on a straddle IMO, is barely worth your time !