Aside from hydrating, you can use moist heat right before they try to stick you to see if that helps. I have horrible veins also (lots of valves which makes it hard to advance the catheter into the vein, and lots of veins killed from phenergan and IVs), and heating pads don't work for me as well as hot wet washcloths. The nurses usually look around to see what looks good, then we let a washcloth sit for about
10 minutes, then they try.
Last time I was admitted to the hospital, they almost put a PICC line in, and I would have been all for it because my veins are weak and IVs don't last longer than a day in me. If a PICC or port are an option for you, I'd definitely consider it.
Do you have your infusions at a hospital or outpatient clinic? Anesthesiologists and nurse anesthetists are really good at starting IVs so maybe you could ask if one of them can come down to help?? I have done this when I'm running out of veins...though I worked at the hospital I go to so I know some of the surgical staff and they are ok with me calling them. Not all nurses are good at starting IVs, and some departments are better at it than others, so don't feel bad asking for a supervisor or someone up front so they have their best try first and don't stick you multiple times before going to a supervisor.
Good luck Friday! I hope it's not a 6 (or 14 :O you poor thing cleanfreak) poke kinda day ;)