well if you look back on your gta history theres an interesting fact
gta1 had three cities;
liberty
vice
san andreas
gta3 onward had one city split up into different areas, and they followed eachother
gta3:liberty city
gta4: Vice City
gta5: San Andreas
now gta2 only had three citys but i dont remember them being named.
as for new gta, try searching gta:liberty stories, coming out on PSP its a return to liberty with the addition of motorbikes and a bucket load of minimissions [like trashmaster where you have to collect garbage and return to depo within a time limit.
and again as you play gta vice and SA you'll see refrences to the old games [characters, photos etc etc] everyone loves a good easter egg [like the big chocolate one in vice]