Subselect query enhancement

I'm needing help determining the best all-around query for the
following situation. I have primary table that holds ip information
and two other tables that hold event data for the specific IP in with
a one-to-many mapping between them, ie:

CREATE TABLE ip_info (
ip IP4,
--other data
);

CREATE TABLE network_events (
ip IP4 NOT NULL REFERENCES ip_info(ip),
name VARCHAR,
port INTEGER,
--other data
);

CREATE TABLE host_events (
ip IP4 NOT NULL REFERENCES ip_info(ip),
name VARCHAR
port INTEGER,
--other data
);

There is quite a bit of commonality between the network_events and
host_events schemas, but they do not currently share an ancestor.
ip_info has about 13 million rows, the network_events table has about
30 million rows, and the host_events table has about 7 million rows.
There are indexes on all the rows.

The query that I would like to execute is to select all the rows of
ip_info that have either network or host events that meet some
criteria, i.e. name='blah'. I have 3 different possibilities that I
have thought of to execute this.

First, 2 'ip IN (SELECT ...)' statements joined by an OR:

SELECT * FROM ip_info
WHERE ip IN (SELECT ip FROM network_events WHERE name='blah')
OR ip IN (SELECT ip FROM host_events WHERE name='blah');

Next, 1 'ip IN (SELECT ... UNION SELECT ...) statement:

SELECT * FROM ip_info
WHERE ip IN (SELECT ip FROM network_events WHERE name='blah'
UNION
SELECT ip FROM host_events WHERE name='blah');

Or, finally, the UNION statment with DISTINCTs:

SELECT * FROM ip_info
WHERE ip IN (SELECT DISTINCT ip FROM network_events WHERE name='blah'
UNION
SELECT DISTINCT ip FROM host_events WHERE name='blah');

From what I have read, the UNION statement does an implicit DISTINCT,
but I thought that doing it on each of the tables would result in
slightly faster execution. Can you think of any other ways to
implement the previous query?

I have explained/analyzed all the queries but, unfortunately, they are
on an isolated computer. The gist is that, for relatively
low-incidence values of name, the UNION performs better, but for
queries on a common name, the dual-subselect query performs better.

The explains look something like:
Dual-subselect:
Seq scan on ip_info
Filter: ... AND ((hashed_subplan) OR (hashed_subplan))
Subplan
-> Result
-> Append
-> various scans on host_events
-> Result
-> Append
-> various scans on network_events

UNION SELECT DISTINCT:

Nested Loop
-> Unique
-> Sort
-> Append
-> Unique
-> Sort
-> Result
-> Append
-> various scans on host_events
-> Unique
-> Sort
-> Result
-> Append
-> various scans on network_events

If it would help to have more information, I could retype some of
numbers in the explain.

Any ideas?

Thanks,
-Mike