One trick that Kim has mentioned is that sometimes if you submit an order and it immediately gets a partial fill, it's worth it to try pausing the order execution (sorry, don't know how this can be done in OptionsExpress), then reactivating it, waiting a few seconds in between each step. I don't know why this works, but it does (obviously not every time). I have success doing this maybe once a month, most recently this week with the GOOG trade. Like you, though, on one of the GOOG legs I only had 1 contract filled.
With IBKR, I can submit option combo orders as all or none, but I've never used that option as I think it would significantly reduce fill %. I try not to let partial fills bother too much so long as I get a good price. Annoyingly, they're just a part of life when you're following the methods promoted here.