We actually do not learn a whole lot about the physical description of Netherfield. We know from Mrs. Bennet's enthusiasm that it is a large estate, though not as large, or as grand as Pemberley. Also, we know that it has a "breakfast-parlour" because Elizabeth is shown into the "breakfast-parlour" when she first arrives at Netherfield to see her sick sister. We also know that it has a formal dining room, or "dining-parlour," because as was expected of that class of society, the whole household dressed formally for dinner. We also know that it has a ballroom because Bingley held a ball at Netherfield. We also know that, as expected for a large manor, the rooms are very large. We see this when at one point Miss Bingley invites Elizabeth to "take a turn about the room" (Ch. 11, Vol. 1). The number of rooms and the size of the rooms of course show that Bingley and his party are wealthy, upper-class, who value their wealth and their social status.
We also know from Bingley and his party's activities that they are gentlemen and gentlewomen of leisure who do not need to work for their income. They fill their time with strolling in the garden and entertaining each other with playing cards, music, and singing. These activities alone do not say much about the nature of Bingley and his party because these are things that all the leisurely upper-class did to entertain themselves.
However, we do see Bingley ordering his housekeeper, Mrs. Jones, to do everything she could to look after Jane. He also frequently had his servants call for the doctor to tend to Jane. These activities show that Bingley has a very kind and caring nature.
One thing we see Bingley's sisters do is gossip and make rude remarks about Elizabeth and her family. These activities show that, typical of the upper-class, the Bingley sisters were very arrogant and conceited.