Hi Simon, welcome to the forum,

I think it best you don't go making a rod for your own back. Gifts are 'not' expected and if you are treating the family to a holiday, then this is more than enough of a gift for them. If you start showing your wealth, then it will be expected later. Just go as an average person, dont splash the cash, be careful not to show you have money and do not be fooled into thinking you have to take them out for expensive meals every night.

By the way, you will not be going 'down' to Tarlac as you have to go 'up to Tarlac from Manila. We wouldn't want you to get lost.