Re: Recommendations wanted - space opera/ big idea sci-fi
Alastair Reynolds' Revelation Space books. Order of reading can be a little debatable but if you search on here it has been discussed on threads around about.
Poul Anderson's Tau Zero and The Boat of a Million Years. They are not related but both cover huge timespans and present interesting ideas. Tau Zero could loosely be described as space opera in that the action pretty much all takes place on a single (very long) space journey. The second is not really space opera until possibly the tail end of the book.
Neal Asher's Polity books - again take a look in his sub forum for help on the reading order.
Brian Aldiss' Helliconia - though that has some pretty strong Fantasy elements rather than space Opera.
If you like military space opera then consider David Weber's Honor Harrington books (On Basilisk Station mentioned above is the first). Also Jack Campbell's Lost Fleet series (ignore the terrible book covers and titles - they really are quite good!).
Other than that I would second some of the other recommendations, such as Hamilton, Banks and Larry Niven (you might also consider his collaboration with Jerry Pournelle; the Moties books beginning with the Mote in God's Eye).