When i need a break from grinding to cap, i pop on net flix and do some free plat downloads. I've gotten up to 50 plat in an hour. How you spend it is your choice, but if you decide to purchase lix in the GH, i would go with a 2x xp on for 5 plat. Personally, i use the 3x xp and 2x damage. the quicker things dies, the faster you can kill more things, and the more xp you can get in a half hour.