Easy Sex Change: Reinstantiation (see Body Surf) into a body of the appropriate sex, if available, will do it instantly; meanwhile, if that’s not available or desirable, a day or two spent in a medical vat while the proteus nanomachines take you apart and reassemble you appropriately will do the job. Neuter and hermaphrodite are, of course, also options.
Of course, this just changes physical sex. Gender identity and sexual orientation are different matters – which are dealt with by appropriate editing (animus-anima remapping, et. al.) of the relevant regions of one’s mind-state vector to suit – a service usually offered by the same clinics that offer the physical change.
(See also: In Just Seven Days…)