WordNet sense 1 (a contented state of being happy and healthy and prosperous):

welfare, well-being, eudaemonia, eudaimonia, wellbeing

WordNet sense 2 (an unaccented beat (especially the last beat of a measure)):

offbeat

WordNet sense 3 (pleasantly (even unrealistically) optimistic):

cheerful, pollyannaish

WordNet sense 4 (expecting the best in this best of all possible worlds):

optimistic