Join Date: Jan 2012
Location: San Juan, PR
Programs: AA EP, DL D, UA 1K, B6 M2, Hyatt GLB, MR AMB/LT, IHG P/A, HH D, FndCd, Sixt D, NTL E, Hz PC, Avis PC
Posts: 466
I keep basically every foreign currency leftover after a trip, and usually hit the ATM for $100-500 in local currency anywhere I'm staying. I keep it in safe or safe deposit box and take whatever I'll need for each trip. I have about 30 currencies and amounts ranging from USD 5 to USD 5000 of each. USD, EUR, GBP, CHF are my "focus currencies", though. I have ~5k in RMB and 4k in THB which is pretty inconvenient.
No interest earned, but it's sort of a hedge, and mostly a convenience thing. Depending on the country, cash notes can get discounts bigger than credit card benefits.