I more often than not do it overland and always enjoy. My usual itinerary is, Liverpool / London / Paris Eurostar same day. Get a hotel near Gare De Lyon for the night. Next day get the 10.10 first class Paris to Barcelona direct, get into Sants about 16.30. Have a pint and bite to eat then jump on the overnight ferry to Ibiza in a cabin at 22.30, usually gets into Ibiza about 06.30. Similar on the return but the ferry is daytime so have a night in Barcelona then do Barcelona back to Liverpool in a day.