Visiting Singapore

If you read earlier threads, then you must have got your answer. We have said numerous times that reach out ICA to find if there is any ban exist against you. If yes, then request them to advise how to clear it.

Why you were denied twice? ICA doesn't deny without any valid reason. No matter who invites you, if ban exist then you will be denied again.

First get confirmation from ICA that you are able to visit Singapore before you make any such plan. Good luck

Your previous work pass application might have been denied because you were employed by a relative - the Singapore authorities do not like nepotism (and rightly so!).
If now another (or the same?) relative invites you for an extraordinarily long visit (the average visitor stays in Singapore 3,5 days!), of course they will look at it very suspiciously - as they dislike circumvention of work pass rules even more.
So it all depends on how convincing is the justification you give for wanting to stay that long. If you only write "visit" or "family visit", I am sure it will be rejected (or you receive only two weeks to a month). But if you, for example, must care for a critically ill relative (and can prove this with hospital records) or a newborn baby, then you might have a chance.

I know not getting an approval for a work visa would have made you wary of visiting Singapore.  But I don't think visiting the country as a tourist would be any problem for you. However, I would suggest that you be honest with the authority person and let them clearly know that you were denied a work visa earlier but are here now just as a tourist.
You can show them the official visiting letter from your relative or your friend. Singapore is a wonderful place to visit and trust me, you do not want to miss the chance. There are plenty of tourist attractions in Singapore, Malaysia and Thailand. You can enjoy a lot of fun adult as well as kids activities in Singapore. So don't worry.  I am sure you will have a gala time there. Just plan your trip already!!!