You can easily upgrade but can’t always downgrade.
When pricing out gym memberships it’s hard to know what services and amenities you will use, many of these services can require and additional charge or longer contract term. For example if you don’t know if you will use multiple gym location opt to do the single club membership, if at some point you need to use multiple locations simply upgrade. If you’re not sure you will use the guest pass perk on a membership wait until you need it and then upgrade. When in doubt don’t spring on extras unless you will absolutely use them, you can easily upgrade but not so easily downgrade.