if your are not making a game nor widget, just plain nice-looking app then phonegap is your choice.
But you should take care with your JS, avoid doing anything in JS
for example if you want to do any animation avoid setting a timer with small intervals (eg. 100 ms), avoid jquery and alike animations. For example instead of animating fade by setting a short-period timer decreasing opacity at each point step by step (this is how jquery fade work), you should use css3 transitions from opacity 1 to opacity 0.
My advice is to go with something like zeptojs.com, after all phonegap won't run ie6 :-)
Check some tutorial on how to make your JS more light
http://bcksp.blogspot.com/
