I've only stayed in the Orchid Tower and felt the fittings already looked cheap. Can't imagine what the other tower is like.To add to this thread, while old this is a post from my stay a few years ago: HSP - A Schoolies Sell Out
Now I have been back several times since, as recent as last month. The same security guard is still there surprisingly but has toned down on the macho since. Still not very friendly though, but has at least dropped the " new security guard" ego.
To restate what has already been said before, you MUST stay in the Orchard tower, the other one is a crap hole in comparison. Every time I book I put it in the additional requests on the booking to put me in the Orchard tower and I request it at check in too. One time even after all that they STILL put me in the other one but they let me change when I pushed.
A bit of background I heard on the grapevine, the Orchard Tower was designed and built by Hilton. The boulevard tower was another project under construction at the same time by another company that went bankrupt in the final stages which Hilton decided to take over. This would explain why the other place is cheap all round from the lack of lifts, thin walls, small rooms and lower quality built ins.
Honestly IMH besides the security issue mentioned before the Hilton Hotel section (not residence) is on par with other properties. I've stayed in some considerably worse Hilton properties in other parts of the world. Even the residence in the Orchard tower are pretty sufficient, especially if you book outside of school holidays you can get some very good rates.