Since I got turbo boost (over 1000 hits a day-wooow) from Tanel Poder the Great, better I write something to deserve the fame. This one is a real quick one which made my life easier.
On my second week at current company, I had to cover Exadata for 2 weeks which were completely nightmare due to some problems. I had to work with Oracle Support too much and most of the time they ask AWR reports from 8 nodes for x hour duration. First day I was not armed with anything automatic, so tried to do it manually but it was proper nightmare for 8 nodes. Then I said this is complete rubbish way of wasting my time and I need to automate the process otherwise my life will be miserable. Finally I came up with something after couple of attempts
The script below is the result of this automation attempts.
define _interval=1 --1 for half hour 2 for 1 hour
define _database_name='DBNAME'
define _begin_interval_date='141111 23:00:00'
define _end_interval_date='151111 05:00:00'
define _folder='C:\PERSONAL\awr\instance\EXADATA\141111'
SET termout OFF
host mkdir &_folder
SET termout ON
host dir &_folder
SET heading off
spool gen_awr.sql
SELECT 'set veri off;' FROM dual;
SELECT 'set feedback off;' FROM dual;
SELECT 'set linesize 1500;' FROM dual;
SELECT 'set termout on;'||CHR(10) FROM dual;
SELECT 'spool &_folder\awrrptto_&_database_name'||CHR(95)||TO_CHAR(instance_number)||'_'||TO_CHAR(previous_snap_id)||'_'||TO_CHAR(snap_id)||'.html'||CHR(10)|| CHR(10)||
'SELECT * FROM TABLE(dbms_workload_repository.awr_report_html('||TO_CHAR(dbid)||','||TO_CHAR(instance_number)||','||TO_CHAR(previous_snap_id)||','||TO_CHAR(snap_id)||',8));'||CHR(10)
||CHR(10)||'spool off'
FROM (
select instance_number,dbid,snap_id,
LEAD(snap_id, &_interval, 0) OVER (PARTITION BY instance_number ORDER BY snap_id DESC NULLS LAST) previous_snap_id,
LAG(snap_id, &_interval, 0) OVER (PARTITION BY instance_number ORDER BY snap_id DESC NULLS LAST) next_snap_id,
begin_interval_time
from dba_hist_snapshot
where dbid=(select dbid from v$database where name='&_database_name')
AND instance_number in (select DISTINCT inst_id from gv$database )
AND begin_interval_time>=TO_DATE('&_begin_interval_date','DDMMYY HH24:MI:SS')-1/24
AND begin_interval_time<TO_DATE('&_end_interval_date','DDMMYY HH24:MI:SS')+1/24
) WHERE next_snap_id<>0 AND previous_snap_id<>0
order by instance_number,begin_interval_time asc;
spool off;
!!!To save it click on the view source link on the sourcode upright corner
Nothing rocket science, just using dbms_workload_repository.awr_report_html with some junior level analytic.
All you have to do is give the date, interval (only tested for half hour or one hour intervals)and folder to be saved then rest will be done by the script.
It will create a gen_awr.sql script which you will run and go have a coffee then when you come back your awr reports are ready to be sent.
so the sequence is
@gen_snap ---assume you save it with this name @gen_awr --coffee break --zip+upload
I would like to automate it further by doing the same for rac comparison or group of instance but I think I am too lazy or maybe busy with some other non-automatable rubbish 
(I also had some issues with rac comparison report formatting with the DBMS_WORKLOAD_REPOSITORY package so I gave up on that one)
Hope this tiny script save your time as much as it saves mine.
