So I, respectfully, disagree with ms. babyblue. It's important to realize that the main purpose of an away is to make friends, regardless if you're shooting for a letter or not... preferrably with people who are part of the resident selection process. You don't necessarily have to be the most outgoing and social person to do an away (although that definitely helps) or get great letters... rather you need to seek out someone to work with who, optimally, matches your 'presonality' 🙂, and has similar goals.. essentially someone who sees a younger version of themselves in you...
As for the competitiveness of programs you do aways at... I'd say shoot for the stars... do it where you'd love to go (cuz it will definitely show during the month)... and if you were the PD of an ophtho program and your best friend were applying... you'd fight for them regardless of the quality of your program, wouldn't ya? But make sure you aren't 'wasting' your time... I question how well-spent away rotations are (with respect to matching... not in terms of learning), where you spend all your time with newly-minted PGY2s, and have only a few minutes a day with attendings...
But, yeah, practically, apply to several aways, cuz they do fill up quickly, and try to fit a couple in... Personally, my strategy was to focus on my home school (which, luckily, is a solid program), and then do aways at dream places that I had no right even considering. I figured even if I didn't end up matching there, I'd know a bunch more cool ophtho peeps 🙂...
Also, you don't always have to do an official away rotation to get to know people... I emailed my CV to a PD at a top program (who seemed to have interests similar to mine) saying I was interested, would be in town for the summer and had no need for credit, and he said "sure, join me in my clinic for a few weeks in May"... so you never know... Of course, I wouldn't recommend doing this as your initial ophtho experience when you're still trying to figure out what "OU" stands for 🙂 Also, remember it's the quality, not the quantity, of time that matters... One of my recs was from a wonderful ophtho big-wig, with whom I spent a total of 12 hrs working (she only saw pts at my school 1 day a week over a month)... I was told during several interviews that it was a 'great and very enthusiastic' letter...