As TheLifeOfA_NKCM mentioned, how many people you can take into the lounge at no additional fee depends on how you obtained your PP card. Each of the major travel cards that offer it seem to have different rules. With AmEx platinum, it would just be you ($27 per guest afterwards). Citi Prestige allows you plus immediate family or up to 2 guests. With Chase Sapphire Reserve, it is the primary cardholder plus traveling companions (the most generous). If you buy a membership directly, I think you always have to pay for guests.

If you have Priority Pass, you may want to consider the Plaza Premium Lounge in Terminal 4 in addition to/instead of the SkyTeam Lounge. I am sure it depends upon the time of day, but I found the Plaza Premium to be less crowded with better food, with an overall newer/cleaner feel. The SkyTeam lounge is still decent (one of the better wine selections for a PP lounge), but that last time I was there I felt it was starting to look rough around the edges. If you want to shower, I have tried the SkyTeam spa area--it was just OK. I know Plaza Premium has showers but I have not used them.