When you have installed the Azure Stack Technical Preview and you are creating your first offer. You have to decide whether your plan will be private or public. Regarding the offer you do not have the choice. If an offer is private the tenant will not see it. So an offer should be always public.
When you decide that your plan will be private, your tenants will not see to which services and location they are subscribing.
Make the plan public and your tenants can see the services.
Because a tenant subscribes to an offer it does not matter if a plan is private or public. Otherwise as a tenant you want to see the services that are included in the offer.