My favourite rum for mixing with coke is Havana Club Anejo Especial. Squeeze a wedge of lime in there and it's perfect.
Try Diplomatico Reserva Exclusiva which is Venezuelan.
I bought some at Christmas after reading reviews and it is fabulous.
Definitely not for mixing with coke!!
Ron Zacapa is one of my favourites, but not as a mixer - neat only. That said the bottle I have has lasted me 3 years so far!
It is delicious but I'm not a big drinker and have it from time to time. (I drink on average once a month if that).
I've had the Sistema Solera 23 which is very nice, and currently have a bottle of Centenario XO (best rum I've ever tried).
Other good shouts for sipping rums are:
Angostura 1919 probably the best value sipping rum available.
Angostura 1824, very nice but not worth the extra on the 1919 imo.
El Dorado 15, superb.
El Dorado 21, almost as good as the Ron Zacapa XO.
Pusser's 15, a huge let down.