I have used oxys and flexeril... (as for dosage im sorry i dont have a suggestion, ive taken both at the same time anytime ive taken the combo) I don't take the flexeril too often I always have a bottle tho prescried for specificly muscle spasms andways other than relief from muscle spams it doesn't seem to add much. Knocks me out every now and then, I believe it's just tiredness though on those days. I agree, I think recreationally it's crap, I'm not advocating but you will get more from benzos or hydroxyzine.
I've always been a fan of cariosoprodol , Soma, and it's a much better drug. I'm a total hypocrite yes, but will repeat, don't get yourself in the spot I have.. dependent on both benzos and opiates. Plus it's dangerous game of CNS depression. Especially when tolerance is a bitch to figure out regarding benzos and what usually comes with them (SSRI,s etc) which is my opinion are awful beyond awful but that's neither here nor there.
Safest I can say and I agree is hydroxyzine is safer than flexeril, I would say safer than benadryl as well. But thats my personal opinion hope it helps.