Tuning 9.3 for 32 GB RAM

Hello,

do these changes please look okay for a PostgreSQL 9.3 running on CentOS
6.4 server with 32 GB RAM (with Drupal 7 and few custom PHP scripts)

postgresql.conf:

shared_buffers = 4096MB
work_mem = 32MB
checkpoint_segments = 32
log_min_duration_statement = 10000

sysctl.conf:

kernel.shmmax=17179869184
kernel.shmall=4194304

pgbouncer.ini:

listen_port = 6432
unix_socket_dir = /tmp
pool_mode = session
server_reset_query = DISCARD ALL
server_check_delay = 10
max_client_conn = 600
default_pool_size = 50

I understand, that nobody can tell me the optimal settings - unless I
provide full source code to everything. And if I provide "the full source
code", nobody will look at it anyway.

So I am just asking, if the settings look okay or if they will waste
gigabytes of RAM.

Thank you
Alex