SEPTA is on strike. Given historical precedent, they may well still be on strike on the day you are traveling. This affects all public transit except Regional Rail, but everyone who can possibly do so is switching to Regional Rail for their commute. Driving is hell and now Regional Rail is apparently hell also, because it is so overburdened. In normal times the R1 would be the best way to go, and you could feel safe leaving your hotel to catch the R1 that leaves Suburban Station at 11:30. But if the strike is still on you may want to think very hard about that. Ask the hotel staff for advice.

See this article from the Philly Inquirer for more color on the story.