If you set your target SDK version in the Android manifest file to "3", then your layout on large-screen devices will be just a scaled up version of what it is on small-screen devices. Once you set the target SDK to a higher SDK, you can create separate layouts for each screen density, which provides a much better user experience.
However, my layout is mainly made up of images, that are high enough resolution that they display just fine on all screen sizes, even when scaled up, because they're big enough that they don't need to be stretched. Now, it would be much easier for me to just create a small-screen layout and have it scaled up, because it would still look nice on large screens. Is there any way I can get that effect without going back to API level 3?
You can use weight parameter.
“weight” is a term that's used to specify how much of the screen a particular view should occupy if there’s any room left after it’s drawn.
Simply make a LinearLayout and place two TextViews within it as such:
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="small"
android:layout_weight="0.2"
android:background="#123" />
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="0.8"
android:text="huge"
android:background="#456"
/>
</LinearLayout>
You will notice how views occupy space accordingly. You can create any layout you want for smaller screen and specify weight attribute and every thing will be adjusted beautifully