From memory, if you choose a simple install, it installs all of the components and gives you the option of installing the SQL database on the same machine and the SSO install can only be made in basic mode which doesn't let you promote the node to multi-site or clustered.
There's no harm doing the install separately and during the SSO install choosing to create the first in a multi-site or highly available deployment, it gives you room to expand if nothing else.