We would recommend just to browse these forums and you most likely will find 90% of information you are looking for. Everybody joining the forums asks for the same things, so we are not supposed to explain them hundreds of times.
There is no definite path until we don't your tastes, however for architecture it is the Old Town of Riga, Pardaugava and Maskavas street, for natural landmarks go to Jurmala or
Saulkrasti/
Vecaki/Skulte/Gauja (outside of Riga), for the hotels check
Riga in your pocket guide; the most advanced hotel for your money is
Reval Hotel.
As for the historical sites, just walk through the town in random order, you will see them a lot
