Having applied very recently, I would say what works best is the quality of the letters... I had one recommender put the address and name of said-director of admissions at the top of each letter. I prepared everything to be as easy as possible on their end, and it seems like it paid off quite handsomely. Perhaps was this futile? Who knows, but if a recommender is willing to go the extra mile, it gives that much more credibility to the rest of the letter.
I had planned to apply to 15 schools, and ended up finalizing my apps for 6 schools. Don't underestimate how tiring the application process is.
On that note, submitting a letter isn't too tiring at all for recommenders, so that wouldn't be too problematic if you choose to do so. I would argue that, in retrospect, focusing on the quality of the app is most important. The two schools I had put in the most effort into (talking to alumni, admissions, doing research, attending presentations) gave me the most scholarship money out of all offers I received.
PS: I had offered a box of chocolates/mini-gift to my recommenders and all refused, saying it was only normal for them to support my candidacy. Once I got my offers, I emailed them and told them that if they have any upcoming students with a similar profile to mine, I would be glad to speak to them. I suspect the thrill of knowing they've placed their students/ex-colleague into a solid program with scholarships is more thrilling than a small gift. Hope this gives you ideas and helps your app process!