Yes - FR have their uses as long as expectation levels are adjusted appropriately (heresy on this board I know!).

Train is indeed the easiest way to get from PIK to the city. The train arrives at Central Station. From there, the Hilton at William St is a 10 minute walk (although it's not the easiest hotel to access on foot - the easiest way on foot is to exit to the left as you come onto the station concourse, turn left and walk 30 metres to the junction. Turn right and walk along Argyle Street (past the Radisson and Marriott) until you reach the motorway bridge at Anderston station, turn right and the Hilton is 200 metres up the road). You can check train times at www.thetrainline.com

It would be a pretty short taxi ride from Central Station to the Hilton (make sure you specify which Hilton), although you probably wouldn't be the only person to ever do it.