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Pls see some suggestions posted on your Finnmarken thread. Can recommend Muddus, perhaps combined with Jokkmokk -village with Sami museum, botanical garden etc. It's a quite remote town, Kiruna more so, not that much resembling other towns in Sweden in terms of setting, economy etc, however arcitecturally it's not too special. Its irregular street pattern was designed to prevent from polar winds. It's more interesting and well-known than Gällivare, the latter with plenty of surrounding natural sights though (the best ones rather remote), and some local sights related to mining.
In the Höga Kusten the most known spots are the Skule hill/forest and Nordingrå area. There are plenty of minor roads around there leading to smaller villages or nature reserves. The area and bridge across Ångermanälven (Ådalen) is quintessential Norrland coast. The nearby Kramfors area is in Sweden most known for its industrial heritage (not many industries left) and the last incident (1931) of military intervention against civilians during a workers' strike. South of that the area is more built-up than perhaps expected, while some newer roads are straight and highly uneventful, different from some older riverside roads. The coast south of Sundsvall also has numerous hidden gems of low-key character, though very little can be seen from the main road (ie detours needed).
A more interesting alternative in terms of driving could be from around Delsbo towards Bollnäs along Ljusnan River and further to Dalarna/Siljan, though a natural sight further east closer the E4 would be (often mosquito-infested, much more so than most of its surroundings) bird sancturay and national park Färnebofjärden, with a peculiar mix of northern wetlands and more southerly-oriented features eg some big oak trees.

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thanks a lot for the help in both threads! The indland route sounds good as well but i think i'll stick to the coast. By the way could you be a bit more specific about the "hidden gems" south of Sundsvall? Again thanks a lot. :)