My answer is "Yes & No"
No, if by "belonging" to a course means you get special privaleges at a semi-private. My experience is that you are still faced with difficulty getting tee times, (especially on weekends) closely spaced tee times (creating traffic jams), and the dreaded "Outing". Most semi-private courses agressively market themselves to corporate and charity groups. Our local semi-private is closed to the public (including members) two or three days a week during the season. So a resounding NO to semi-privates.
Yes, if you can see yourself clear to join a private country club.