Wireless bridging

[coolVariable]

Helping someone with their wifi network and wireless bridging.
The internet is on the first floor but some computers, etc. are 2 stories up and do not get a signal from the single router downstairs.
So ... the idea is to wirelessly extend the network so the other floors have a good signal too.
Bridging via cables is not an option sadly.
They got 3x wireless routers that support wireless bridging: Belkin F5D7230-4

Which setup is better? (| = cable ; ~ = wireless)

Internet
|
Router 1 Wifi Net #1 (with 1-2 PCs connecting via wireless downstairs)
~
Router 2 Wifi Net #1 (used only as a bridge to downstairs)
|
Router 3 Wifi Net #2 (with 1-2 devices connecting via wireless upstairs)

or:

Internet
|
Router 1 Wifi Net #1 (with 1-2 PCs connecting via wireless downstairs)
|
Router 2 Wifi Net #2 (used only as a bridge to upstairs)
~
Router 3 Wifi Net #2 (with 1-2 devices connecting via wireless upstairs)

or should I get another wireless router so that the setup is as follows:

Internet
|
Router 1 Wifi Net #1 (with 1-2 PCs connecting via wireless downstairs)
|
Router 2 Wifi Net #2 (used only as a bridge to upstairs)
~
Router 3 Wifi Net #2 (used only as a bridge to downstairs)
|
Router 4 Wifi Net #3 (with 1-2 devices connecting via wireless upstairs)

 

[Agamar]

Why not use your second access point as both a bridge and AP? No need for dual APs

 

[coolVariable]

I seem to have a peculiar problem that opening multiple tabs on a computer (that is connected via the bridge) "crashes" the main router.
The main router will be up (wifi signal can be seen) and computers connected via wired can continue accessing the internet ... but no PC can connected until I reset the router.