Chris - IMO the 60* is plenty of loft but, there are some pins that you just can't get at and you have to be content with 10ft past for example.
I'd spend some time experimenting with different shots with the 60* you already have. The lie etc obviously dictates what sort of shot you can/ can't play and gives you an idea of what result to expect as a best case scenario.
One technique I've found useful when needing a little lofted shot which is too close to spin is as follows: Set up as normal with the 60* have the shaft pointing vertically. Grip very lightly and swing a little slower and longer than you would normally not conciously trying to accelerate the clubhead through the ball. The ball will tend to pop up and feel "dead" off the clubface with little forward momentum.
If done correctly it will land where you want it like a wet tea bag
I think the 64* and any more loft are novelty clubs that you get little use from, a bit like putting a left handed club in your bag just in case you go up against a tree!