The first day I would build
Give the city one clear route before adding extras.
- Start with Omar Ali Saifuddien Mosque and Kampong Ayer while energy is high.
- Use Royal Regalia Museum as the natural reset instead of crossing town too early.
the easier plan is Omar Ali Saifuddien Mosque and Royal Regalia Museum first, Kampong Ayer by boat, Gadong or Kiulap for food. That keeps the day readable instead of turning every good name into a separate detour.
I would rather leave one place for tomorrow than drag a tired route through Tamu Kianggeh just because it looked close on a map.